If you have had played Wolfenstein: Enemy Territory, you will be extremely familiar with the objective based gameplay that Brink pushes onto the player. I was a gargantuan fan of Enemy Territory so this may be one of the reasons why I enjoy Brink so much so take this small review with that in mind.
The combat is what you would expect from Call of Duty, lots of hip-shooting and aiming down the sight. The weapons all seem to be very similar and it appears to be like this to accentuate the weapon upgrade system and to try to find some form of balance so everyone is not using the same weapon. All of the unlocks are earned by doing very easy challenge missions, that allow you to go 'hey, that dudes upgrade is awesome! I want that!' then head over to the weapon customization where this list the unlockable accessories, and how to get them all in the same menu section. Customization doesn't end at the weapons, but continues onto your body type which affect how much health you have and the speeds and parkour you can do. There is also a ton of cosmetic clothing you can unlock for your character which will please some people.
After about thirteen hours I have really grown to enjoy the game and feel comfortable with the mishmash of oldschool Enemy Territory objective based class play and Call of Duty aim-down-sight style of game. All of the classes mesh well and feel unique while the different stages of maps provide enough of a change that I think I will get a lot more replay value out of the game.
My 2 cents from an ET fan.