I just played my first ranked games today. I actually hesitated for around 2 weeks after buying the game, even though I had been playing vs AI for around a year now.
I knew about the mechanics thing, about macro being more important, and I just had to bring myself into doing it.
I instantly quit all my qualifying games so I would be ranked as lowest as possible; figured it would be alright since I had never played a human. Got Silver 1. Then I proceeded to lose the next 5 games. But each one of them was funnier than the other, to the point I was laughingg while tapping out. The reason being because it was pretty obvious I could beat all those guys if only I knew more about the game, about what units to make and whatnot. I just need time. And that made me pretty happy about it, and I'll be playing more in the future. At the end of the day I'm pretty happy that even though I lost all my games, I managed to contain a terran with lings and banes just because I could produce units faster than him, but I didn't know how to break it so that was about it.