So I just got back from seeing Underdog with Lil' G-Girl. I gotta say, I really did enjoy it. If you overlook the typical, cutesy Disney stuff, it really wasn't bad. Jason Lee's voice even felt right the further into the movie we got. I grew up watching Underdog and recently started watching it again with G-Girl now that they've released a dvd boxed set. They included lots of elements from the original show. That's what scored them some major points with me.
So not a great movie but as an Underdog fan, I approved.