I liked everything about this game. I can't list everything because they only give you 300 words. Everything is just so well done, and it's all so cool. I will say that I particularly liked that there's only three guns (mostly). A pistol, shotgun and assault rifle. I think it was kind of brave for the developers to do that, but I didn't find the lack of variety boring. Each has it's own strength and weakness so each one get's a good workout.
There's also a large section of the game where you don't get any guns at all and have to rely on a blade and stealth. This was also brave of the designers. It warrants a word of warning though… it requires patience. You must stalk your enemies, wait for just the right moment, then sneak up and cut their throat. It can get dicey and in one or two parts frustrating, so this may not be your cup of tea if you don't like that kind of thing. But they didn't go overboard on the difficulty.
I found the difficulty at a good level for me throughout. I expect every game I play to get stupidly difficult at the end, and have some big boss or something, but not here. The difficulty is manageable, although challenging at times. I didn't find it too frustrating and I didn't have to cheat.
If you twisted my arm I'd say the architecture is a bit samey, but they did a good job of making the levels interesting even though they are quite linear. I could go on about the characters and voice acting and story, but like I said… only 300 words.
It's quite lengthy but it doesn't drag on. I was enthralled to the very end.