Ninja Gaiden Black

The Good
The pace is quicker than anything I've seen in any other game before. The story is good, but takes a backseat to the action. The action is smooth and fast and satisfying. The sounds get a little bit repetitive, but compliment what's happening on-screen very well. The graphics are great, the enemies are varied and none of them are pushovers. The cut-scenes are awesome.

The Bad
The ending is very anti-climactic. If I cared more about the story than the actual game play, I'd be very disappointed.
The moves get a little repetitive on later playings.
This game is really damn hard. It can get very frustrating. Extremely frustrating.
I wish the bodies could pile up instead of disappear, but I hear they've changed that for the 2008 sequel. The chronology of the game does not relate to the difficulty of the bosses. You can encounter easy or hard bosses at any point.

The Bottom Line
If you stick with it, and don't get discouraged, it's very rewarding. Passing a section that was giving you a lot of trouble feels great. The best game I've ever played.