I'm not far enough into Blacklist to give it a meaningful review, but I'm enjoying it so much I had to come post about it.
I got it for free with my geforce graphics cards, but I honestly think I would pay full price for it....and I RARELY buy a game full price.
A lot of reviews have said that the gameplay is a healthy mix of old splinter cell (ie chaos theory) and Conviction, and I would have to agree.
There's a Mass Effect feel to it where your mission hub is on a plane that you can walk around on, upgrade, talk to your crew, and view a 'map' of different campaign missions, side missions, and online multiplayer options. I like it, and the fact that there are so many ways to complete each mission (ghost, panther, assault, co-op, etc.) and several levels of difficulty to try, means that there will be plenty of replay value to the game.
I haven't given co-op a spin yet because I have no Ubisoft friends, and I wish they would have given me a Steam key instead, but oh well.
So far, I highly recommend it if you enjoy splinter cell and/or stealth games in general. Also, the game is gorgeous. I'm on PC, maxed out at 1440p and it's just lovely. If you liked Tomb Raider, you're gonna love the way this game looks.