From what I have observed so far from the current game play and PvP battle report review, IMO the races' is pretty much imbalance in SC2.

Yes it does have counter over this and that; but in RTS, rushing and mine resources dominance in the INITIAL starting game STAGE is the main key to win. The Terrain race simply gaining too much advantageous in SC2 if compare with other races. I think terrain race will dominate the most winning in MAP battle. ...No offense, just my opinion... who knows after patch #x.xx, everything will be balance back like SC1 I think