It's better than the second, but again, not nearly as good as the first.
Some of the new characters are very interesting, like Agent 9 the monkey, because he has a laser gun, and can use bombs. There's also Bentley the Yeti, he has a huge ice club that can break things like boulders, but he's very very slow. He's kinda fun to play as.
Sure the graphics still suck and the levels aren't as interesting, but it's still fun to run around finding Gems and lifes. Something that might make you mad however, is the Tank Blast challenge, it's rather hard and boring, and to even be able to play you have to solve a riddle. (Which is easy) But it's only one challenge. Slides are very fun as well because not only do you have to stay on the slide, but you have to collect the Gems on your way down.
There is a fun unlockable level that I'm not going to spoil for you people who haven't beaten the game, but I WILL tell you that it involves a bunch of minigames. (Only a few are actually fun though)
You still travel from Homeland to Homeland in order to get to new worlds, but the Homelands aren't as interesting. The game isn't as hard as the first either, but it does have a decent length.
Pros: Good length. Some fun minigames. Lot's of characters to play as.
Cons: Easier than the first. Levels aren't as interesting. Graphics are crap.
If you don't own this game for some reason, you should get it, but be warned, it's not as good as the first.