Unlike many fans, I don't have an issue with Goku not being cast as an asian; he was a bloody ALIEN, for crissake, and was originally based on the non-human Monkey King, so getting all snippy over the human racial descent of the actor is ... silly.
James Marsters might be a decent choice for Piccolo; he seems to at least have some knowledge of the character, which is better than casting someone with no knowledge (or worse, distaste for the show).
Chow Yun-Fat as Kame-Senin, now there's an inspired bit of casting. One of the very few bright points.
Alas, the dark points...
Released photos are extremely unencouraging. Yes, they're just sets, no post-production material, but... I'm not very hopeful. I suppose it depends partly on budget for the effects and re-construction. Set photos for some of the other more heavy-CGI films aren't very impressive either.
Leaked plot is the worst, though. Okay, I can understand merging Goku and Gohan to an extent (Gohan of the Great Saiyaman era, in high school). But apparently he's BULLIED? I'm sorry, that's so DIRECTLY counter to Son Goku that I can't even grasp it. Goku's always been a fighting prodigy, and moreover his personality is utterly wrong for anyone who gets bullied; he doesn't even UNDERSTAND bullies, wouldn't put up with them, and if -- by some chance -- the bully was actually badass enough to get away with it once or twice, the bully would just be pushing Goku to find his next level. And he wouldn't be bullied by being knocked down and taking his lunch money; if you were going to bully him, you'd have to literally beat him unconscious.
Originally I thought they were going to just do a sort of fast-forward of the plot from early DB, get Goku and all the main characters introduced, and then move straight into the Piccolo saga -- probably the Ma Junior Budoukai. I suspect part of that is, in fact, what they're doing, but it sounds very much like they've totally screwed the pooch on this one.
It's also possible that this is deliberate -- i.e., that this is the modern version of the Roger Corman Fantastic Four; they're making the movie to fulfill last-minute obligations, have no intention of releasing it, and were forced into it due only to the ending of the option time.
In which case may all concerned burn in HFIL.