Just finished the game. Took about 10 hours on medium. A friend also took around the same time, so I think that's typical if you take your time. Only difficulty came when they threw like a dozen soldiers at you, or when those grenade lobbers showed up, forcing you to abandon your cover.
Gameplay wise I'd say it's competent, the Blacklight thing was nice although I rarely remembered to use it. QTEs weren't too bad. Aside from the RE4-like melee fights, they only show up like 5 or 6 times in the entire game. Even the stealth sections were okay, although having to time your triangle press to take out an enemy from behind felt unnecessary.
Had some weird glitches happen, such as the weapons menu not showing up sometimes, or some weapons disappearing, and one time an enemy was just standing around despite my being mere meters away. Very infrequent, though.
The game will be enjoyed mainly for its presentation, and it excels there. Really amazing attention to detail. And unique setting, too. Too bad the story seems to abruptly end.
I enjoyed my experience with the game, but I don't think I'll return to it. The game doesn't even tell you what collectables you've missed on which chapter, and you can't skip cut-scenes.
What difficulty would you recommend to new players? Another gaffer who beat it early said he thought rolling through on hard your first time would be the way to go. I guess it depends on what you're looking to get out of it.