So I've been in the beta since the first week (lucky me), and I feel like I should share some of my thoughts thus far.
As a hardened SC veteran, I'm probably a bit more jaded than most. When you've spent years playing, and following the scene of, the most balanced and skill-intensive RTS ever, that comes with the territory. So naturally I have some gripes about the balance, and especially the map quality so far. I really expected amazing maps, and I'm kind of disappointed that once again it seems like the community is going to have to provide that avenue of balance for the game.
Anyway, I've played both Terran and Protoss at the mid-high Platinum ranks (and if I can get past my annoyance over the map pool I'll be playing Zerg this time around). Overall, I'm not too worried about the racial balance or anything like that. It's more important that each race is unique in play style and unit diversity. The macro mechanics help make each race more diverse, however there is still a bit of stagnation among the unit ranks. This is hard to judge, though, as you have to take into consideration the fact that so many more people are playing for keeps now. So many people are working to be the best at this game even though it's still in beta and far from complete.
An interesting thing I noted when I took about a week off of SC2 due to lack of interest (and hope that patch 9 would include a working map veto system), is that playing Brood War during that time actually continued to help my game. So for those of you who plan on playing the hell out of SC2 when it comes out, practicing SC1 in the meantime will definitely help. Despite the difference in mechanics, the sheer amount of actions you can and need to perform in BW will make your SC2 game much more proactive.
So if there are actually any of you out there wanting to practice some BW, feel free to stop by #starcraft on irc.synirc.net (same as the smogon IRC). As noted in the BW thread, there's a group of 7-8 of us who play and discuss the game from time to time. Myself and the couple others who actually have SC2 beta keys will also be glad to chat or game SC2 as well.