Feudal Japan is alive and well here.
But down to the most important part: the gameplay. When people think hack and slash their thoughts usually turn to repetitive button mashing and monotony. Genji remedies this problem by giving you four unique characters with multiple weapons that can be switched on the fly, which really opens up different combos and different strategies that can be explored over the entire 20+ hour experience. Personally, I never got bored but my opinion is biased since I am a fan of the genre.
The camera is definitely a problem. The right analog stick is used (very well) for evasive maneuvers of your character, so no manual camera here. You are stuck with what the game gives you and expect to take a good deal of cheap hits from off-screen enemies. In my opinion, however, this never becomes too big of a problem considering there are usually healing items and save points nearby.
Another issue is that the level design is sometimes frustrating and doesn't give you any advice on where to go next, so don't expect any "waypoints."
But these issues are minor and I believe the scenery and music easily make up for this. Most of the bad reviews come from people that don't like hack and slashers in the first place so they shouldn't even be playing it. However, if you are a fan of the genre I highly recommend it because it's one of the best.