I just feel that there are lots of encounters in the game and people are singling in on the more restricted combat areas to prove the gameplay is mediocre (along with binders of reviews to back them up), while there are lots of more open areas where you have a lot more ways to approach them and where gameplay is more fluid and dynamic. Those were the areas I enjoyed the most but a lot of people seem to pretend they don't even exist.
Personally I liked the mix of restricted/open environments, with shooting/stealth segments, but I can perfectly understand why other people wouldn't. The issues I had weren't with action gameplay segments, but with the relatively static environments and path finding during the exploration parts.
Tactically I never felt like I was given a better option that "remain in the same spot and wait for the enemies to reveal themselves". It felt like playing the worst of single player CoD, but with a cover system most of the time.