I got my key via Gamestop. Just preorder it for 5 bucks and you get a key. Not sure if it's US only though.
Anyway, the game is great. I didn't play much SC1, but if you read around, a lot of the pros are saying that SC1 is better. However, they do say that SC2 is only in beta and it could get better.
There are some OP units (Immortals, Mauraders, Voidrays, etc.) but they can be countered easily if you scout correctly and what not...well does that make them OP then O_o. But yeah, a lot of people cry about those units.
Graphics are top-notch as well. But as far as I know, all Protoss and Zerg players are gay. 2 Gateway proxy Zealot rush is gay if you're not prepared and for a newbie like me...I get crushed by it all the time.