Death Jr. Root of Evil for the Wii fixes a lot of problems featured in the PSP version, but it's incredibly short.
There's one obvious flaw when it comes to Death Jr., it lacks originality. The atmosphere is certainly unique. Not many games have the Tim Burton esque style (except maybe Psychonauts and Voodoo Vince), but the gameplay has nothing that a lot of other platformers don't. Gameplay is basically Ratchet & Clank. You have guns, and you have a scythe (instead of a wrench). Some of the guns are cool, but a lot are very basic. Shootgun, electric weapon, pistols, been there done that.
Even with the lack of originality, Death Jr. is a lot of fun. This may be bias because I love platformers, but the game plays very well. The controls are smooth and I have fun playing it. Platforming works (thank god!) and there are some relatively unique moments even if the gameplay lacks any hint of originality. Boss battles are fun, even if they are a little generic (another giant plant? Puh-lease). They often require you to think a little bit which spices up the gameplay.
Graphics look lovely. It has a fantastic artistic style to it, and the graphics are technically proficient as well. Comparing PSP and Wii screenshots, there is a significant improvement in the Wii version. I feel like I'm playing a Tim Burton based game a lot of the time, and I'm comfortable with that.
Humor is hit and miss. The game can be very funny at times. Dead Guppy is obviously the best character. On the other hand, the humor is also a little childish for me. Maybe it's just the way Death Jr. talks, but the stuff that comes out of his mouth sometimes just makes me groan.
The game's major problem is the length. The game can be beaten in about 8 hours. It features 2 different campaigns, but they're nearly identical, and it's obvious from the start. You get different controls, but they all kind of control the same. And combat is identical.
Overall, I enjoyed Death Jr. 2. It's a fun platformer that is unfortunately plagued with a short campaign and a lack of originality. However, you could play a lot worse platformers on the Wii. Quick note, if you're forced to choose between Death Jr: Roof of All Evil and Ninjabread Man... pick Death Jr.