I've actually only watched one episode of this show on T.V., but that was enough to intrigue me. So I've purchased all three seasons on DVD. I think the only thing that frustrates me about this show, especially season 3, is the lack of the story arc. I'd really love to see movement on one of the two major issues in Monk's life: the case of his wife's murder, or getting re-instated to the police force. Not that I need to see him solve that case or be reinstated. But in 16 episodes, you'd think they'd go back to these parts more than just the first episode of the season. But they didn't really, despite several episodes with dream sequences with his wife.
I've loved police procedurals in the mystery novel genre, and generally like them as T.V. shows. Monk is great for these. It's like Encyclopedia Brown for adults. And despite the fact that Monk's phobias invariably pop up at the worst possible time, and it can usually be predicted, the writers always seem to make the occurrences fresh.