The show starts out hilarious, and then starts to get funnier and funnier, then dims down a bit, then gets really funny, then it's over. Note: when I say dimmed down, I mean, only a little worse than the rest of the episode.
I think Adult Swim exaggerated a little when they said it was the best episode. I enjoyed other episodes a lot more. The plot is bizzare as ever, but I just wasn't laughing as much. One thing you should know about this episode, is that this one, above all others, shows the Mayors stupidity. This is a good thing! I found Joy's Ex (the person, not the episode) annoying, really, especially after he leaves home.