As far as movie based games go, Kung Fu Panda could have been a lot worse.
Kung Fu Panda is a beat em up platformer. The combat, while not amazing, is a lot better than most movie based games. It's not really complicated. X is fast, Y is slow, B is a special attack. B either lets you roll around and knock people around Sonic style, or if you jump and press it, you can body slam your foes Snorlax style. This adds a remote amount of fun and makes the game easier. You have many ways to upgrade your attacks at the end of the level which you earn by buying them with coins. I'm happy the game has an upgrade system, because it helps spice up the combat, unlike a lot of button mashers (I'm looking at you Afro Samurai!). There's no way to by new attacks unfortunately, but the ability to upgrade is good enough for me.
The game adds some interesting objectives other than just beating up a bunch of baddies until you reach the end of the level. Certain levels you have to protect artifacts, others you have to scale walls to drop the ball (literally!). Most movie tie-ins are pretty linear, but Kung Fu Panda tries it's best to spice things up. You even get the opportunity to play as other characters, and they're not exactly the same, they actually have different attacks (woah!)
So the combat is good, and it's not completely linear, what else? Oh, the voice acting isn't half bad. Mainly from Po. Although he isn't voiced by Jack Black, you probably wouldn't notice unless you were told. I've heard some good impressionists before, but this dude is ace. Another positive about the overall presentation are the graphics, which really replicate the style of the movie.
Sadly, Kung Fu Panda does have some VERY noticeable flaws. One of the biggest is it's length. Kung Fu Panda will take you about 5 hours or so to complete 100%, if you want to just fly through it and ignore the collectibles, the game might take you about 3 1/2 to 4 hours. The quest for 1000 gamerscore may keep you coming back for more, but it'll probably take you about 10 hours to get the full 1000, which still isn't THAT long.
Bosses are repetitive and dull. Most of them require you to avoid a bunch of attacks and enter a couple quick time events. I'm a fan of quick time events, but when it's the whole boss fight, it gets disappointing. I enjoy bosses that make me think a little, these are obvious to beat.
The camera isn't always on your side. In fact, it seems to go against you at the worst times. Numerous times during the tougher battles, (as tough as this game gets of course) the camera decides to freak out and you end up getting hurt.
Overall though the good outweighs the bad in Kung Fu Panda, which means a lot for a movie based game, the lack of length and occasional repetitive gameplay is a bit of a bummer, but I can name 100 movie based games that are way worse.