This is my favorite game on the Wii since No More Heroes. It's just as absurdly over the top, but even more stylish.
The visuals, straight out of Frank Miller's Sin City (more the comics than the movie, since there actual panels in the cinematics) is the most striking thing I've seen on the Wii. The voice acting is great (and hilarious, in the case of the profane announcers played by Greg Proops and John DiMaggio).
Best of all, it controls very well. The motion controls don't feel gimmicky, as they're used well and sparingly (although you will occasionally lose a life or two due to reacting a split second too late during motion control based quick time events during the boss battles).
Those boss battles are very reminiscent of God of War, and not just because of the quick time events. They use each stage's set piece very well for dealing out massive punishment to your adversaries.
This game is the uber violent Sin City story Frank Miller never had time to create. It's also the spiritual successor to No More Heroes and the closest thing the Wii has to answer to the God of War series. So, if any of that appeals to you, definitely give this a rent. I can't speak much to replay value (I can't imagine I'll ever play through it again), but I thoroughly enjoyed my two weeks with it. I mean, I liked it more than Resident Evil 5, and I liked RE 5.
Mad world is the most violent game I've ever played the graphics are pretty awesome all black and white (but in a good way) with blood being the only color. To tell the truth the only problem is it's short maybe 6-8 hours long. The game is just awesome within the first hour you probably spilled 17 gallons of your enemy's blood so as the title suggest if you like blood you'll love this game.