I've played a couple of hours so far. The combat is really, really deep, and really cool. Easily the best part of the game. Enemies aren't crazy difficult, but when they hit you they really hit you. Mobs are very difficult to deal with, at least for me.
The mood of the game isn't nearly as oppressive as a souls game, which makes it easier for me, but the inspiration is everywhere.
I don't like the loot system, it's just way too much. Think of the First Mass Effect and Diablo. In the first two hours I have picked up the same couple of items with different specs at least 20 times, which then requires constant equipment changes and muddles up the inventory screen. I hate that, it just seems pointless to me.
All of the ninja and samurai stuff are awesome, and the leveling tree looks incredibly complex. It will be really easy to see a thousand different permutations of warriors from people playing this game, and I already kind of have by fighting the constant revenants littered throughout the game so far.
For those who don't know, revenants are AI versions of real human players that have died in specific spots in the game. You see a glowing red sword on the ground and you can choose to fight the AI "human" to try and get cool gear or whatever. These guys are pretty hard, much harder than the regular AI.
Anyway I'm having fun with the game but I'm admittedly not very good. The combat is so good though that I don't really mind the difficulty.