Wait for the expansion...
Brink is a good looking game with an interesting setting but really that's it. The single player campaign is short and fails to develop any characters at all. The intro cutscenes for each of the 14+ missions are exactly the same - four nameless guys stand around trying to ramp up each others courage, harangue the one guy who offers a shred of doubt, and justify the next mission in loud angry voices. I started skipping them after awhile. That's a bad sign.
Beyond that the missions also had problems. The most annoying problem for me was the schizophrenia of your opponents. Most missions have you racing against time to capture something or defend something. Now before the countdown hits the final 3 or 4 minutes your AI opponents all act like morons. However when time is getting close to running out suddenly they become special forces snipers. It's clear that this is partially intentional. Often when you fail one objective there's a fallback objective. Fail there and there's another. Obviously the game designers decided they wanted to ramp up the AI at certain points to stack the odds so that you'd fail the first objectives in order to prolong the mission. That's annoying. It would be better if the enemy AI was set somewhere in the middle difficulty range during the entire mission instead of bouncing between easy and elite when time got tight.
Multiplayer is solid but not particularly thrilling. Nothing really new here. There are issues with weapon ranges right now in multiplayer. Weapons often seem to do more damage at extreme range than up close. Great for snipers but not for everyone else. Certain weapons also seem useless in multiplayer because they are too unsteady, or dont do enough damage, or both. So for weapons you've got less choices than you might at first think.
The parkour system is interesting and has potential but still needs polish. The maps are decent. The class system works nicely. The rewards and unlocks as well as the system of character customization offers some cool options.
So in conclusion this is not a bad game, but it needs a patch or two and some more content before I could really recommend it enthusiastically.