So I've played through the co-op and the campaign. While I was enjoying it, it has a very common problem. It's over too quickly. Difficulty as well is merely a case of not being detected in the levels that require it, and not necessarily retaliation.
For instance, I played through both the co-op and campaign on "Realistic", and beat them both. Problem is, 80% of the game can be beaten via typical combat approaches, and really ruins the need for hiding. The other 20% requires you to stay hidden which is such a jarring difference on "Realistic" that it can be keyboard-smashingly frustrating at times. The lack of an ability to move bodies in "Realistic" quadruples the difficulty simply because every target has a flashlight, and sees bodies more easily than they see you.
The story, while interesting, was too quick and seemed rushed. There wasn't much in trying to figure out what was going on, and the twists had me literally scratching my head. The lack of choice here was a problem. I felt like I always had one, maybe two ways to go or to deal with issues, most of which degenerated into simply shooting and not bypassing.
Now for all it's faults, I will say the one major thing that impressed me was the change in animations. They were all a lot more smooth and natural in comparison to previous titles in the series, however that doesn't excuse the rest.
Now as far as character designs, I do have to scratch my head there too. For one, Sam looks younger in Conviction. Why? This doesn't make sense. He's supposed to be older, much older. Archer's costume design is annoying as hell. He has a set of goggles that look like they are designed for night-vision with depth perception over one eye like an eye-patch. It just makes me want to punch him in the face each time I see it. Kestrel is at least believable.
