This game has the potential to be a classic if they patch a few things. Namely the AI and the cover system.
The last part is the AI, now it seems it can either be down right brilliant or completely moronic. There were numerous instances where I was in the line of sight of an enemy and they did nothing, didn't move and didn't even notice me and this was like 5 feet away (granted it was at a slight angle, but still). I would kill their companion who was standing right next to them and nothing would happen. Mind you, didn't happen everytime, but enough to kind of ruin the experience. The AI at other times could be brilliant, they throw grenades and flank you. They do work together and will try and push out of your cover spots.
Really, those are my only complaints, otherwise this game is fantastic. Terrific dialogue, NPCs and story. With actual consequences! I've never before played a game where you can see the actual results of your actions so plainly and immediate. The combat is fun and engaging and despite what people say, the stealth is possible but you have to invest the points into it and plan on taking a much longer time to complete the levels. The check point save system kind of blows and I wish it were not there, but it's a small niggle. Overall, I think Obsidian has done a find job on their first IP and hoping to see more from AP in the future.