got this today, played for about a couple hours...
Lots of fun, I've died quite a bit just from being stupid and not paying attention to my health meter.
The levels are big, and have lots of areas to explore, monkeys take you to hot springs. I bought food and stuff in a city, there was ghosts. Ninjas are a bunch of fun to kill, it's great when a group of 8 appears and you just kill them like an awesome ninja should. Bosses are fun, fought a giant ninja turtle wannabe, and 3 giant centipedes. You get more swords on this huge branching path with experience you get from killing, and each sword has a new skill, so its almost like a skill tree.
It feels like I'm playing a fully realized NES game about ninjas, and that's a good thing. The pacing, the music, the vague story, and the action really feel like an NES game.
Can't wait to play more. Its good fun, and its gorgeous, it's really great looking.