TL;DR:
If you want to play an objective based game, if you want to lay mine fields and build turret nests, or if you want to slide tackle and pwn them with a silenced shotgun, then Brink is your game.
If you're too impatient to learn how to play it, or if you don't like stylized graphics, or if you don't like objective based team play, then you should pass I guess.
My best advice is to ignore the reviewers and just watch the gamplay. If it looks like fun to you, then give it a shot.
That was my strategy at least.
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I was on the fence for a while, and a combination of this review as well as a the opinions of a few people at Machinima Respawn [http://www.youtube.com/watch?v=wJEYXGy0Uco&list=SL] convinced me to buy it.
I'm 10 hours in and having a blast.
Single player is lacking a bit. I tried playing through the whole campaign single player, but I wound up getting stuck on the mission Ship Yard because of the AI issues people have been mentioning.
The AI is a little annoying in the fact that your friendly AI prioritizes all of the secondary objectives above the primary main objective, to the point where losing control of a secondary objective will cause allied AI teammates to leave the primary objective, even if it's half complete.
The other issue with single player is it is the multiplayer. The only difference between single player and multiplayer is how many humans are attempting the mission.
That said I really love the class system, I really love the SMART movement system, I really love slide tackling people with my shot gun and then running away with my light character, and being a mobile machine gun nest with my heavy engineer.
As far as the SMART movement system being "unintuitive" or "glitchy" if you play for a little while you recognize which sorts of objects you can climb, and which you can't.
As far as the interface being confusing, I think it's because the game dumps it all on you at once. There is a "tutorial" in the form of "challenges" that you need to complete to unlock weapon attachments, but the challenges don't really say, "Hold Shift to use SMART, press Mouse 3 to pull up the objective wheel." Or even, "This is a command center, this is what it does, this is why they are important to capture for your teammates."
Once you have a base familiarity with the game, either by completing the challenges or looking through the control list and then fiddling around, I don't think it's that complicated. There's just an initial barrier to entry that's slightly steeper than the one for say, COD or Halo. And honestly, that should be expected, considering that the game features a unique movement system, a class system where every class has unique abilities, and an objective system, whereas COD or Halo do not.
Finally, I really like the character customization aspect of the game. You create characters who level up and unlock points, and you unlock outfits and weapons for all of your characters as you play. I was really thrilled when my Engineer looked precisely like Mike Tyson.