Well I wrote a huge comment under the video already, but here will be more constructive =)
I liked the idea of brink (class based shooter with objectives!)
Where it failed:
a) too lineair maps (I hoped more battlefield like terrain)
b) unlocking skills?? -> this is my main downfall, classes need the skills to work together. But right now everyone just picks the class they got the most skills for (Engi or Medic normally) and not the class most needed!
c) weapons: so much choice and so little differences or alot of useless ones.
d) no class bound items - appearance -> this is something new makes it fun, but extremly hard to balance
on paper: great
online: not so much.. Just to hard to for attacking sides, small maps with lineair mapping,..
Yathzee made a good point, but I doubt adding more classes will help unless they dumb the skill system! Make levels only award clothing would be a huge step forward!