The game world is fairly detailed and downright beautiful, but the guys at Splash Damage prioritized "belivable architecture" and "aesthetics" over functionality, the battles were pretty unbalanced because of this. Now, some would argue that real world architectures are not meant for a videogame and that's a fair point, but that would be the case if this game wasn't multiplayer focused, meant to be played many times over the same maps, also let's consider that many maps use makeshift shanty towns made out of containers, so that's not an excuse.
Also, most of the weapons felt pretty samey, you could grab a machine gun and modify it however you wanted and make most of them feel almost exactly the same. The customizations for both weapons and your own character was astoundingly awesome, but the downside being that classes were basically unrecognizable, even Planetside 2, Tribes and especially Team Fortress 2 gives you visual cues to clearly distinguish wich one is wich, Brink had a fabulous sense of fashion, but at a really impractical level gameplay wise.
Speaking of classes, you could change classes on the fly and that was awesome, but you couldn't change your body type and that was a serious hindrance for strategies, you couldn't hop into a "Scout-esque" class if you were a lumbering tower of muscles meant to take a ton of damage and you couldn't do an offensive role if you were a skinny straw meant to run at a thousand miles per hour, so basically everyone picked the middle class and specialize on neither.
The bots in single-player are downright attocious, also it had a quite hefty number of technical issues at launch, like AMD cards being basically useless for the game (I think the issues were resolved either by a AMD driver update or a patch for the game) and the netcode was attorious for using P2P base code, sure, they added dedicated servers a few months later, but it was a little too late, everyone just basically gave up on the game.
And lastly, nowadays is a barren desert, an online game is made by it's community, no matter how shitty it is, if it has a loyal following, it may survive for a few years (20 for Doom or 16 for Quake and both with fairly active communities, especially Doom) and Brink basically lasted no more than 5 months.
