I've heard it's great from everyone, but the demo I played did not impress me. It was basically a demo of the fighting system where countless goons keep getting thrown your way - The fighting system felt like a series of button mashing though. I wasn't impressed outside of the voice acting and graphics.
I'm sure the full game is totally different though, so I should probably give it a chance.
It's like Metroid with brawling instead of shooting.
If you slow the combat down and push the buttons punch for punch, the fighting is actually pretty complex. If you just mash it gets pretty frustrating.