Honestly, AoC had a *remarkably* smooth launch on the "server stability" end of things. One of the smoothest I've ever seen. There is a lot of things which remain unfinished, but then again there have been a TON of things enhanced in WoW since launch.
My major complaints about AoC include: "Feats" i.e. wow talents descriptions are utterly useless, to the point that a person cannot make reasonable intelligent decisions about which ones to pick based on their descriptions. Not to mention there are numerous feats which simply don't work. Combat mechanics are very nearly a black box, again hampering decision making & optimizing effectiveness. Class balance is utterly broken- the "pure" tanks (guardians) do more damage than the "dps" tanks (conqueror) by nearly a 2:1 margin. Funcom chose to shorten the levelling grind, so it's a lot shorter to get to 80... but that also shortened their window to actually get an "endgame" together, so unless further development of an endgame shows up fast, a lot of folks will get to 80, and realize there's not much to do at 80. Those are pretty much the most egregarious problems I see. I'm putting AoC down and waiting 6 months to take another look, as it's clearly not ready yet.