BECK is one of my favorite anime. Not only the anime, but also the manga and off course the movie.
If I were to choose, I would prefer the anime. Eventhough the movie itself is not that bad. It is just that I got irritated everytime Koyuki sing. Because you won't hear his voice at all. They said it is because they want to leave it for our imagination. But, watching beck means I want to hear the song. That is the main reason I choose the anime instead the movie. (but, i fell for Osamu Mukai as taira from the movie :p)
btw, all the song from the anime were awesome. Don't you guys agree? Addicted to it until now :p