Balance things:
1. As I've stated before, the flying medic is ridiculous for Terran, and IMO less of a viable strategy than the field medics.
2. I do NOT like how you can not mass-employ a given super power (i.e. multiple nukes, multiple 120mm cannons, or whatever power). Unless I'm missing something.
3. For some reason, I could not 'blink' teleport my Stalkers behind enemy troops when they were being attacked.
4. I miss Reavers. Colossus is a welcome addition, but not Immortals... (IMO of course)
5. I know an update was needed, but just keep some of the original designs of the first game for crying out loud - did the probe REALLY need a redesign? I like continuity in a game, and how flashy you can make it game to game, not how often you can redesign something that doesn't need it.
6. This is just opinion. One reason I liked Starcraft is because of the ART. Look at the CG cutscenes, then look at the first game. Looks awesome, and so vastly different from other Bizzard games. Now look at WoW, its sprites and art direction. Now look at the Zerg in SC2. Its like I'm playing WoW as the Zerg, seriously. I liked the Halo Flood-type vibe I got from the Zerg, now its like controlling WoW. Major turn-off for me, very seriously. The way things are animated and move looks like its from WoW.
Take apart and criticize as necessary