Alt-text: 'ARE YOU TURNED ON YET?' 'I DON'T THINK SO--ARE YOU?' 'MAYBE A LITTLE!' 'OK, FIVE MORE MINUTES.'
Okay, as SinbadEV said, this is actually a pretty decent comic. It does have a fair share of problems, but it's still an appropriate "real 1000th strip".
What I like the most about it is its perfect pacing and execution of the joke. The first three panels depict the consequences of a stupid decision (a man and a woman spinning on a bed a bit too fast) and the last panel reveals the decision itself (to build said rotating bed at home after seeing one on TV). Randall even managed to avoid all the usual pitfalls. No post-punchline dialogue, no banner that says "PARTY", no unrealistic speech. Well, okay, it seems a bit stiff to me, but not nearly enough to ruin the comic for me.
The art is pretty good, too, at least for xkcd's standards; I have to point out the ripples in the sheet and the screams of "AAAAAAAA". On the other hand, it isn't very well depicted that the bed is, in fact, spinning, apart from a mediocre blur effect, and the big faceless heads in the first two panels really seem out of place, like in just about any other well-drawn xkcd strip ever.
The weakest past of the comic, though, is the alt-text. It's not funny, it's just really, really stupid. Shame, especially since there are many things that the alt-text could say that would fit the comic a lot better. Here, let me try: "An unidentified flying object has been sighted near Boston. One of the passengers of the circular spinning vehicle has been reported to say 'WHEEEEE!' ".
All in all, this is probably one of the best strips Randall has drawn in years, and I'm glad that it has come right after the horrendous 1000 "comic". Please keep the quality up, Randall.