I like brink, though it does have a serious lack of variety. It most definitely needs some free map dlc before I feel I got my moneys worth.
One off the odder quirks that probably should be redone is the body type system. There seems to be a very small variation in health between heavy/medium/light, and move speed for heavy/medium is near identical. Since Brink is such a movement oriented game your best bet is to go light, then just keep moving and use the slide move to knock down enemy players so you can lay a clip into them before dashing over a barrier to avoid his buddies. Get yourself the Kevlar upgrade (soldier self-boost, engineer teammate buff) and you have near the same survivability as a heavy player, with double the speed
The only real reason to choose another class is if you want more weapon variety, (mainly assault rifles, shotgun, and the infamous heavy gattling gun). Even then I find the bulpdaun SMG (final SMG unlock) with accuracy boosting attachments and a high-capacity clip, to outdo many of the assault rifles in range and power, without sacrificing mobility and on-the-go spray and pray. As far as secondary weapons go the Hockler MP (Steam pre-order bonus) is devastatingly effective for surprise close-quarters combat (actually it feels kinda OP for me, which might be the reason it comes with a frustratingly small amount of ammo.)