I think that Cowboy bebop shares one thing with jazz: it's not for everyone. You either "feel" it and let yourself be taken by its flow (a nice, lazy flow), or it's just a bunch of random notes thrown together without much sense. So, I would dare saying that the anime itself is a kind of jazz piece.
Note: this is not an insult to anyone. For me, jazz is a kind of music that yu have to feel, and you have to be in a mood for it to enjoy it to its fullest. Personally, I'm not really a jazz person, and I usually find it tiresome and just too random.
That said, I enjoyed CB a lot and it is one of my favourite anime.
The movie is also great, but more in terms of a well-done action flick with a bit of the CB spice. Also, it stands pretty well on its own IMHO, which is pretty rare.