Ironically, the actors who were arguably the three biggest names in the film didn't really do much with their roles: Dennis Quaid, Christopher Eccleston, and Joseph Gordon-Levitt. They're all three solid actors, and I was expecting a lot more from them than I got. Quaid in particular seemed to be phoning things in. Eccleston was probably the best of the lot, but his Destro wasn't a tenth as engaging as his Ninth Doctor. Gordon-Levitt? Well, the heavy makeup, costume, and voice treatment didn't do him a lot of favors, I guess.
I actually really liked how Gordon-Levitt portrayed CC in the movie. I was actually shocked. It reminded me of Heath's Joker (in the sense that the casting made you think wtf but it turned out to be good). I wouldn't say him as CC was on the same level as Heath's portrayal of Joker but he still did far better than I thought he would and I really liked his version of CC, I just hated that crappy mask at the end.
One thing that kinda bothered me was how other Joes made an appearance but didn't do anything. I was susprised to read that Lady Jaye was in it (not sure what part but I am assuming it's somewhere during the parts where Duke and Ripcord were training).