I bought SC II a few weeks after it came out, and played obsessively for a few months. My inner gamer got the better of me, and I spent most of that time achievement whoring, managing to get all of the campaign and exploration achievements, as well as a decent number of the Individual v. AI and Co-op v. AI achievements. I ended up quitting SC II about 2-3 months in, partially due to the realization that playing the game is incredibly stressful, partially due to Terran imba (At first I was just going to quit until Reaper-rushes were nerfed to oblivion, though later this was less of a reason) and partially due to just getting bored. Zerg felt weak and boring, and I didn't really like playing very much.
My biggest problem was that as a race, Zerg was just bleh. I liked the idea of Mutas, but I could never make enough of them to do any real damage. Add to that the fact that I didn't understand the whole idea of expanding and I would only face Terrans that went for MMM balls or Reaper rushes. On the rare day that I'd get matched against a race other than Terran, it'd always be a Toss that would rush Voids or DT's, and I didn't understand the power of Queens or the reason for getting Spores if they aren't going to defend against air.
I was bad, and the overall metagame was so poorly constructed that I was just screwed. I didn't have the mechanics or the skill to play at a level that would let me innovate and define my own metagame, but I also had no idea what to do to improve and stop losing.
I got back into SC II around September of 2011, largely because it seemed there was more depth to the game than when I had started. A large influence in my return to SC II was actually watching the player Destiny execute crazy, yet awesome strategies as Zerg, and I attribute most of my drive to improve to a desire to emulate his play style.
I played aimlessly for a few weeks, then watched streams nonstop in an attempt to learn how to properly play. Eventually, I found a thread on TL asking for bronze, silver, gold and plat level players that were willing to play a lot, try new, or frowned upon strategies, and quickly rise through the ladder ranks to masters. And that is pretty much my entire Starcraft II career up to this point. =D