I realise a lot of people have already written about this webcomic, but here's my own reactions and analysis of it. Oh, and have a couple of icons:
The story so far...
Way back in issue 8.39, Buffy saved Spike from being burned to death by Possessed!Angel - which explains why he's covered in burn scars at the start of this webcomic. He was rescued by the crew of his bug spaceship (don't ask) just in time to witness the effects of Buffy breaking the Seed and the invading demons being sucked back into their own dimensions. Spike interpreted that, naturally enough, as another victory for the Slayer - it's not obvious from context if at this stage he knows exactly what she did or what the side-effects will be.
Spike decides he doesn't want to hang around while "the good guys... lick their wounds" - instead he's going to make himself useful by chasing after one of the biggest of the demons which didn't get sucked back to hell. That's both practical and heroic of him, but I think there's also a large amount of avoidance-of-Buffy going on, given that when last he saw her, she was still cooing over Angel.
The monster he was chasing also looked like a giant floating vagina, which led to all sorts of Freudian speculation about the symbolism of him chasing after it - but apparently Georges Jeanty was simply asked to draw a large flying demon, gave it a vertical mouth, and didn't realise what it resembled until numerous fans pointed it out to him. In this webcomic the emphasis is put much more on the demon's eyes and body instead of just its mouth...
Now read on!
The story is narrated by one of the bugs - the one which Spike will later give the name Irene. I'm therefore going to refer to her with female pronouns, even though I'm not entirely convinced that Spike can tell the difference between bug genders rather than just picking names at random. :)
Her voiceover is kind of cute; there's a naive, uncritical admiration of him which seems child-like. Of course, there's the expected contrast between her words and reality; for example when she's proudly talking about "showing off our fastest setting" to Spike, he's being held against the bulkhead by the acceleration looking half-dead and totally out of it. I do wonder if there's meant to be a parody here of the Slayers' hero-worship of Buffy in the previous season, taken to ridiculous extremes in the way the bugs feel about 'King Spike'. (There may also be a reference to the 'After The Fall' version of Spike?)
The bugs' methodical approach to catching up with the monster is contrasted with Spike's impulsiveness: he sees a big red button on the console, assumes it's a weapon and presses it. Irene is impressed by his accuracy in firing it, even though technically Spike did nothing to aim the 'gun' - more uncritical hero-worship. There's maybe a continuity error here, since we saw in 'Last Gleaming' that the ship does have at least one big cannon that Spike ought to know about. On the other hand, firing that cannon required the opening of a big hatch on the front of the ship, so maybe it can only be fired in an atmosphere, not in outer space.
I laughed out loud at the reveal of what the 'gun' actually does. Why on Earth, or off it, would the bug spaceship need "a device for impregnating space whales"? Do they run a whale stud farm? Is impregnating whales a common pastime out in the galaxy? Can whales not impregnate each other, but need bugs to do it for them? It's just gloriously, ridiculously silly.
Of course, it's possible to interpret the next part in a dark manner. Spike accidentally impregnates a vagina demon with his huge cannon, which causes it to burst and tear itself apart. Yet another Jossverse nightmare pregnancy that's fatal for the mother. Clearly Jane Espenson hates women-- oh wait.
Maybe they weren't aware of the symbolism; or maybe it's a deliberate and knowing parody of their own favourite story tropes. Given how over-the-top it all is, I lean towards the second. Maybe someone should ask Jane next time she does a Q&A.
The spaceship gets covered in pink gooey exploded demon bits, and so do the crew inside the spaceship. Now, aren't spaceships supposed to be, you know, airtight? And we know the spaceship has air on board, because even though Spike himself doesn't need to breathe, his cigarette needs oxygen to burn. Handwaving about "closing intake vacuums" doesn't really help. :) On the other hand, it was funny.
There are also possible physics errors in the gravity situation. On the first page, the ship appeared to be in zero-G: Spike was pinned against the bulkhead by the acceleration, then floats forward to grab the chairback and reach the controls. Technically, if the ship were still accelerating, he shouldn't be able to float around like that; he'd be treating the back wall of the ship as the floor. Unless the bugs cut the power when they saw he wanted to move forward?
But then the vagina demon explodes, and suddenly Spike is able to walk around or lie on the ship's deck as if it were the ground of a planet with gravity. It doesn't really make sense... unless the bug ship has artificial gravity, but while they were chasing the VD they turned it off to divert all power into the engines? Yeah, that would make sense, kind of.
(Given Jane's writing background with nBSG and Caprica, two shows I didn't watch, I have to ask: did those shows present outer space physics realistically, or in a space opera fashion? Babylon 5 or Star Wars?)
Spike's "heroic, uplifting" speech to the bugs is extremely unlike Buffy's usual inspirational speeches, but by contrast is greeted with wild chants of enthusiasm by its audience. Definite parody. :) It's also funny that he pressed the big red button because he didn't want to endure "one and a half thousand hours" of chasing the vagina demon - but the consequences of his impulsive action will instead take... exactly the same amount of time to fix. Ooops.
The progression of Spike's demands from the deeply serious to the novelty calendar is good characterisation, though I think he's channelling Buffy a little in the way he's distracted mid-speech. I'm curious to know what he's smoking and drinking: are they bug-cigarettes and bug-alcohol, or do the crew have human beverages stored away for some reason? Presumably they also have blood in stock, although given that Spike has been on board the ship for a while, I assume that's been dealt with off-camera.
Also, it's apparently now canon that yes, vampires need to use the toilet - just in case you were wondering.
The fact that Spike carves B+S inside a love heart on the table has already been noted by just about every reviewer of the comic, often in gleeful tones, so I won't spend much more time on it. I do wonder, though, if it was in Jane's script or if Georges put it there on his own initiative? (Though if he did, both Jane and Joss would, presumably, have signed off on it - so it's canon that at this point, Spike luvs Buffy 4eva.)
Oh! and also, he wrote B + S, not S + B. Clearly he knows who's the boss in their relationship. :)
After a week with nothing to do, and only bugs to talk to, Spike is clearly letting himself go. He's only usually such a slob when he'd depressed (see: 'Lovers Walk' - which again makes me wonder if this funk is due to simple loneliness and boredom, or if he's imagining Buffy is riding off into the sunset with Angel now. Remember, he doesn't know about Giles.) He's drinking heavily and he's cradling those discarded bug legs like a security blanket.
Also, is it me or is the bug on that calendar in a sexually explicit pose: on its back, with its legs spread and one hand posed coquettishly behind its head? In other words, is that bug porn? o.O
But over the next few weeks Spike pulls himself together and starts a new life. The montage we get is important because it's showing all the sides of Spike that he normally would let few if any people get to see. There's not just the snarky brawler here. He's a networker, a romantic, a dork, a poet and a nurturer. Not only is he a poet, but he's someone who understands the technicalities of poetry. He even shows off his flair for interior design.
A few side points: I liked that the bug romance novel 'Love Comes on Leathery Wings' was apparently written by Jane Espenson. She should write it some day. :) On a related note, the bug marriage ceremony he officiates for : I wonder if it's simply a ménage à trois or if the bugs actually have three sexes? They also apparently like dancing with giant ladybirds - a pun which works better in American English - but need "chaperones". And Spike using baby bugs as weights in his fitness routine is, presumably, something he's doing because they enjoy it. Awww.
And then after 62 days in space, he returns to Earth and the ship drops him off at Fort Point - to only mild surprise from a couple of joggers who are clearly used to seeing alien spaceships landing in San Francisco.
Buffy's there waiting for him... which poses an interesting question. Did she see the spaceship landing and rush out to meet it? Or did Spike locate her from orbit and tell the bugs to land next to her? Either way, they're hiding their eagerness behind a facade of not caring very much. Buffy's holding a stake, which suggests she was out patrolling at the time, and she definitely loves those woolly hats. I've seen a few people criticising her coat as pretty ugly - I don't suppose anyone recognises the style or who the designer would be? Because I'm pretty confident that the artist would have based it on a real design - and I'm sure that six years ago Georges Jeanty never imagined he'd spend his time researching contemporary women's fashions to draw them in a comic book. :)
The scene has been much analysed already, of course. Bear in mind the context: it's two months after the Seed broke and Angel killed Giles, and so at least two months before the coda in 8.40. Buffy is still living on her sister's couch and feeling like she betrayed everybody. The awkward scene in 8.40 where she gets tearful at Spike's sympathy and flees back indoors is still in her future here.
So here, she's not gushy - though there's a definite "falling into a long-established groove" about their conversation. She's challenging him, hands on hips, at first - but there's a definite vulnerability in her "So you're home for good now?" question, boosted by the hint of a tear in her eye. Spike is playing it cool - but we know from the "B+S" heart that it's an act. Plus, of course, there's his final words of the comic:
"They'll wait for me."
He's talking about the bugs, and I do think his two months with them taught him, once again, that he can find a life for himself if he needs to. But of course in the context of Buffy asking if he's home for good, his serene confidence that "They'll wait for me" probably doesn't refer to the bugs at all. :)