Jesus crap why do people keep stupidly comparing Brink to TF2, that is not a valid comparison. Yes they have a class based system, but that is like saying that GTA is Halo because they have guns or that Starcraft is chess because you control units. Is the market really so devoid of class based shooters that TF2 is the only one that comes to mind. In TF2 (in the beginning at least) you made one choice and it would give you a character with a purpose, damage/health output, appearance and weapons. But in Brink you make many choices with purpose (class), damage/health output (weapon weight and body type), appearance (customized look) and weapons (gun itself) AND variable perks.
In TF2 your class choice is everything but in Brink your class is just one of many decisions.
You know what Brink's class system should be compared to: Battle Field 2142, Alien Swarm, the original Tribes, and of course other games by this developer that came out WAY WAY before TF2 like bloody Castle Wolfenstein and Quake Wars. This class based system in Brink is the same system that they have been using for over a decade.
The tones of the games are different, the weapon systems are different (in Brink there are a lot of "direct" weapons like assault rifles while TF2 has asymmetric weapons like sticky launcher), the objectives in the game are different and Brink has grenades.
Why do people keep comparing Brink to TF2, is it because the graphics are slightly "goofy" in a way slightly and unintentionally similar to TF2?