Brink was a big disappointment.
Let's start with what Bethesda did right: customization and objective types. Brink offers some great character customization having the three body types, and a huge variety to outfit them. Brink also offers some great and creative objective types that really requires a well-balanced team, as well as good teamwork to achieve.
And now for what Bethesda didn't do...
The SMART movement system seemed like a great way to keep the action heightened with players taking different vantage points and paths to take out the enemy and complete objectives. It actually is a good system, but the multiplayer maps just don't accommodate for that and only have one or two spots in which the system can be used, and it is more orchestrated than actually finding a shortcut.
The multiplayer/singleplayer is actually seamless, but when there are huge teams of players, and there is ever only one or maybe two other players in the match with you, it defeats the entire multiplayer perspective. You can't actually join a multiplayer match, you set your match to if you want other players joining it, and then hope that one or two will fall into it, which usually doesn't even happen: this is what really cripples the replay value.
There are only a few maps to choose from, which offer the same feel and the same objectives. This along with almost always just playing with AI makes it feel the same every single time.
The gameplay isn`t bad with a fun feel, but it just doesn`t have an outstanding sense of accomplishment with you kill someone or complete objectives: the game just keeps moving on.
Brink had a lot of potential, but fell very short of a great game: a broken multiplayer system, the same feel and same game every time makes it have no replay value. With a few adjustments, it could have been a 7.5 or 8.0, but it just doesn`t have much to offer.