I'm not finished with this game yet, but I think that I'm already able to write some thoughts about it.
The first game was a good launch for a new series, even more being a bloody game, what is rare in Nintendo Wii. Unfortunaly, the game has many problems in it execution... but life is good, and the game was largely improved in the sequel!
You don't have to ride your motorcycle in the open city (dude, how I hated it in the first game), now you just have to select where you want to go from a menu. The game also has a more appeal to the Travis's nerd side: You are able to play his moe game, and even watch the opening! All the side jobs and training are now 8-bit mini-games (except for the last one), and this is really fun, nostalgic, and well done. During the story, you are able to play as other 2 characters, not a big deal, but it is cool to play with new faces.... despite the jump control of one of the characters is horrible. The plot is full of nonsense and absurd stuff, and not taking this serious is what makes the game funny.
Problems? Yeah, it still has. The lack of variety of enemies persists, and the button-mashing without a variety of controls also continue (the basics are cool, but that's all). And I felt that the bosses fights were less creative and easier than the previous game, but still are the best part.
If you liked the first game, even if it left a bitter taste in your mouth, I highly recommend playing this sequel.