Little improvements go a long way and make this the best action game I've ever played--at least until NGII arrives!
Everything works. Graphically, though it's from the last generation, it still manages to look very pleasing and as good as some new-generation games. The gameplay is astounding, fast, frantic, fun, stylish, and overall it is what makes this title such a kick-ass thing. The combat is fantastic and Ryu proves easy to control in almost all instances, and the level design is unmatched in action games. The many environments are all unusual/unique as well as well-designed. There is some backtracking; however, it is done in an unusually tasteful way that feels hardly like backtracking at all. It feels natural and adds a whole new versatility to the later stages of the game, as almost literally every level in this game is seamlessly inter-connected with another.
There are some very minor flaws that may be worth pointing out: The plot lacks some amount of substance; however, the game doesn't boast this, not does it detract whatsoever (and the cutscenes make it look kick-ass even if it isn't...) The camera, while improved from Ninja Gaiden (Xbox), still isn't always perfect. One my most recent playthrough, however, it failed to get in my way more than once or twice--and neither time was anything near life-threatening or endangering. It is mostly difficult during the few acrobatic sequences...
The score, some may find, is sometimes lacking--which is worth pointing our; however, I enjoyed the variety deeply, and it definitely serves as a score that is easily identifiable and nostalgic for those who have played the game already.
So, overall, Ninja Gaiden: Black is an incredible experience, and, though it is difficult surely, it is not one to be missed under any circumstances.