I think we stopped for two real reasons; our favourite part of the game (World vs World) was the least developed and received the least post-launch love, and burnout. We played a lot, and didn't make easy on ourselves. But the game has come a long way, and I still dip in.
It depends what you're after Q - go in expecting something like WoW, you won't like it. Go in expecting a new take on MMO gaming and you might love it. Has some great ideas, PvE is good, but very different (no trinity, for example). PvP is excellent.