Gameplay wise it is a pure button masher, but what makes it really awesome is sword swipes can actually sever an enemies limbs/head/body depending on where hit. I've cut people diagonally across, sliced off chunks of their back, cut off their foot, whatever. When you hold the left trigger you go into a focus mode where time slows and you charge an attack, targeting where you want it to land. If the enemy is low on health (they'll get a deep red shading on their model), he/she will usually be severed right where the sword lands.
Graphics are great and very stylish, voice acting is just like in the anime, and the presentation is overall well done. While the core gameplay concepts of quick attack, strong attack, and kick can seem dull, the limb severing and presentation make up for it. It's also worth noting that so far, the story has stuck pretty close to the anime. There are also half naked stripper samurai with huge boobs.
Worth the $16 I spent for it at Gamestop.
Forgot to mention it, but the music also kicks ass. I think I read a long time ago that the beat of the music changes the AI's behavior a bit. I haven't noticed anything like that though.