Maybe I'll give a full review later (weekend maybe) but right now the game is really a lot of fun. I had no idea what to expect really- the info in the couple days leading to launch was good, but I didn't know if it was actually warranted. It starts off slow, but once the nemesis system kicks into gear, it's a lot of fun. Assassin's Creed and Batman had more vertical game play, and sometimes I feel like the orcs are nearly blind, but those are the only real issues. Unlike in either of those two games (AC in particular) you really can't feel unbeatable in any encounter. Normal grunts are easy enough to dispatch, but you never know when one captain (or three!) are right around the corner. They have strengths and weaknesses that, for the lower level captains, don't mean much. But when they get some of their better specs (like immunity to certain types of damage, or strengths like super fast health regen), you actually have to give it some effort.
The way I played, I was late to unlocking some of the super awesome powers (I still don't have them, I took the long story route). That should make it way more interesting as well.
Starts out kind of button spammy and easy, but you quickly feel like you got your money's worth. Just give it some time.
oh, and the finishes/kills are awesome.