I tend to agree with everything Yahtzee said here.. including that he didn't "get" it.
I mean, one of the things he didn't get is that it's not really a class based shooter. In TF2, your class is everything. It's how you approach the game, it's how your enemies deal with you, etc. In Brink, your class is just a specialization. Your enemies don't deal with you any differently if you're a medic than if you're a soldier because you've got most of the same abilities regardless.
And that works in reverse as well. Whether you're a medic or a soldier, you have the same basic abilities to deal with threats. Where your class starts to matter is when you start to get really good. Then those minor differences between classes (soldiers with more grenades, medics with self-revive) start to make a difference. Actually, it's kind of like dealing with the differences in a specific class in TF2 now. Does that pyro have a backburner or a regular flamethrower? Bow and arrow, or sniper rifle? That's the kind of difference that the "class" of Brink makes.
But the real "classes" like TF2 have are in the body types, heavy, light, and medium. And like in TF2, those are instantly distinctive. You know if you see a heavy, he's probably going to have a gun that will tear you apart, so you need to definitely stay out of his line of fire. You also know if you see a light, he'll probably go down quick.. if you can manage to draw a bead on him.