I'm playing the Beta, and well... I have mixed feelings about it.
The revamped graphics and stuff are awesome, no doubt about it, and they left the whole Starcraft feel to it. So you have a lot of pleasant remembrances from Starcraft 1 while playing it, as most of the units are exactly the same. Actually, ALL of the units are pretty much exactly the same. It's still fun and all, but I doubt that it will appeal to any players who didn't play Starcraft 1. So many other RTSs have A LOT more to offer than Starcraft 2.