Though I have seen some episodes of the Dragonball anime, I can't at all claim to be knowledgeable in the story or characters, so I won't be judging the movie on any of that. So is the movie entertaining? Surprisingly, yes. Is the movie silly? Definitely. Is the movie satisfying? Not really. This isn't because they botched the execution somewhere, there just wasn't enough of the movie to get to the really entertaining parts. I felt like, you know, this would be really fun if it were a 26 episode series, but as a 90 minute movie, the compression of events is just too severe and we lose too much characterization and plot buildup.I thought Justin Chatwin did a decent job with his character. I don't really care for the Master Roshi character, but I thought Chow Yun-Fat did a good job with it at least as far as my memories of the series go. I can't say much for the female characters, but they seemed the weakest to me. James Marsters as Piccolo was interesting and I would say he did a good job if he had more than a few sentences of spoken dialogue. And Ernie Hudson? Seriously? That was a surprise...
I can see how children would really enjoy this movie. It was entertaining and it showed glimmers of being more enjoyable, but never really made it to satisfying. Of course, it's clearly set up to be a series of movies, so I expect we'll get some future opportunities to see where the live action Dragonball franchise goes.