I started playing against real people (I've only been playing as protoss so far), and it's a whole lot different than playing against the AI. I'm doing the practice league for now, and am 2 and 3 in my first five matches. About the only thing I don't like about the matches at this point is that there's all those rocks everywhere, so it turns into a race to see who can make the biggest air force the fastest. Most of my matches have been Protoss vs Protoss, with one or two terran fights in there.
I'd make sure to send an observer over to see what the other player was up to, and I'd regularly see a big mass of void rays forming. Admittedly, I wound up doing the same, since it makes it a lot easier than slowly plowing through all those rocks so ground troops can get through.
Had one opponent that fast-tracked to colossi, and sent a couple in now and then to harass my drones, and he wound up making a huge army of archons that I didn't know what to do with, especially since most of my forces were void rays, and they weren't putting much of a dent in those things.
It's been interesting seeing what real people throw at me, but I do hope there aren't too many more matches with those boulders blocking ground troops. It just seems unrealistic in that setting for getting used to what I'll find in more normal matches. It's only the first five games that are like this right? In any case, I fully expect to get my ass handed to me plenty more times in the coming weeks, but every match has been a learning experience, so hopefully I'll get a little better every time that I play. =)