Didn't even finish my free month.
I left WoW for CO, as WoW had run it's course for me after almost 4 years of playing. On first impression CO was pretty impressive. Very nice visuals (once you removed the awful thick black line) and lots of character creation options. But, that was all expected.
Sadly, as you play the game you start to realize that there really just isn't anything to the game. I realize that they will add more material as the game grows, but for god's sake! Only 5 zones!? And 2 are only accessible around level 30? The game just didn't have anything in it to keep you playing once you hit about level 25. Even the 'make your own nemesis' idea wasn't very fleshed out.
Ultimately, I just got tired of it after a couple weeks. And, like many, I moved on to Aion and am happy with the decision.