The only real innovation here is in the character cuztomization.
Really, when you look at this coldly, it's another one of those "Log in, die fast, die often" shooters. It's got incredibly intricate levels which allow for flanking from so many sides that you're essentially surrounded at all times. Your foe may come at you from above, in front of, either side, below or behind you. What this ends up producing is a lot of scenarios where you spawn, move, and die because there's simply no way to check every conceivable angle before someone supernaturally headshots you from clear across the map.
The few maps themselves are a mixed bag. Some, like "Aquarium"- although it suffers from that Flank From Everywhere problem -are fun and lead to good back-and-forth battles between sided. Others, however, like "Container City", are just atrocious map design. If you are on the Security side, you've lost as soon as the map loads. You'll be lucky to get out of your spawn area. If you're on the Resistance side, you have to be completely inept (every single player on the team) to lose. It's that clear cut.
In the end, Brink is going to have its share of fans, but overall it's going to slip into mediocrity and be forgotten as just another twitch shooter.