I still think the movie overall sucks even after watching it in theaters. Bad script, bad acting, virtually bad everything. I know people will call what I'm about to do "nit-picking," but I call it "$#*+-picking!"
I don't get why Piccolo needs the Dragon Balls to take over the world when the movie demonstrates he's capable of flattening cities and that he's strong. If anything, the movie never specifically states what Piccolo's wish was going to be except you have to assume it's world domination. I don't get the impression he wants his youth back and doesn't look as aged as the original King Piccolo was. I think Marsters as Piccolo wasn't as bad as I thought it'd turn out to be, but I think he could have been more useful. I think it could have been cool during the fights he loses an arm and regenerates it, or turn into a Super Namekian. Also, it doesn't explain how Piccolo was free nor does it explain the relationship between him and Mai that deeply. Was Mai in prison with him or something?
And it also doesn't explain how "oozaru" was defeated along with Piccolo the first time and how he was reverted into Goku. Bad script writing on virtually every level.
I thought Jamie Chung was going to deliver the worst performance, but I think she did better than I thought as well. It shows her character knows a lot about ki, but I don't get why her character didn't use it. I wish it also explains why and how she can train at that temple. As for Justin Chatwin as Goku, he comes across more as a (very terrible) American version to Makunouchi Ippo from Hajime no Ippo/Fighting Spirit than as Goku from Dragon Ball.
The final fight wasn't really much to write home about - just horrible Sci-Fi channel special effects. I've seen better demonstrations of Dragon Ball ki attacks in after effects videos on youtube. And Roshi using the kamehameha to heal Goku was also a horrible idea that I couldn't bare watching. The movie could have just conveniently introduce senzu beans in that scene instead.