Any game that can keep me smiling is a great game, if it makes me laugh that's even better.
I was constantly screaming, "YES!", when I would chop some guy's (or woman's) head off or cut them completely in half, of course, I'm a sick individual who enjoys that type of thing, hehe. Your greatest sense of accomplishment seems to be when you pull off a harder combo and watch the ensuing chaos of flying body parts and blood. The game play and plot was awesome, even with never having seen the anime. Fighting was more than just button mashing (tried that once, just for kicks, and didn't do so well), and you need strategy to get yourself through the game, a bit of blocking here, a bit of rolling there, etc., or you will die quickly.
Others have said that the camera angles were terrible, but I didn't find that to be true. The correct application of the right stick and your camera angle is the way you like it, and I think it was made that way on purpose, so that you would have to move your own camera and participate more, instead of just relying on the game's camera position.
I'm not much for button mashers, or combo games, but Afro Samurai's combos are easy to remember. I've seen reviews that said there was no combo list, yet a simple touch of the select key and the combo list is given to you.
Afro Samurai was a thoroughly enjoyable game and I am absolutely happy that I rented it and I plan on buying it in the future. It provides tons of laughs and fun in the utter disregard for the way human appendages seem to want to stay attached (as well as the head and torso), as well as Ninja Ninja's little comments along the way.
My advice is to rent the game (which couldn't hurt you) and buy it if you really love it, if not, send it back. But, I warn you, if you play the game through, and take the time to really learn the controls, combos, and how to work the camera, you will have fun and become easily addicted to the game. ;)