Late 2004 I beta-tested both World of Warcraft and Everquest 2. I was impressed how feature-complete and bug-free WoW was running. There were some server issues, but EQ2 had even more of those. And EQ2 was full of bugs, and major game mechanics were changed with every patch, leaving a distinct impression of an unfinished game. But even unfinished games get finished eventually, and I read that EQ2 is quite nice and stable nowadays. Only by now they obviously missed the boat, and only have a fraction of WoW's subscribers.
Early 2007 it's deja vu all over again. I beta-tested both Lord of the Rings Online and Vanguard. And this time it's LotRO which makes a finished impression, and Vanguard which isn't. Vanguard just announced getting rid of the naked corpse run, and I'm sure they are going to fill up all those empty areas with time, so in 2 years or so it could be a quite playable game. But who is going to buy Vanguard in 2 years?
If you buy a MMORPG you go for the market leader, or the recently released game. You don't buy the game that had bad reviews 2 years ago, hoping that it has become much better since then. Even if you wanted to, finding a good source for a review on how a game is 2 years after release is hard. A Google search just keeps directing you to the original, unfavorable reviews. You need to read a lot of blogs, and often between the lines, to get an idea how a game has evolved.
I just hope that the game company managers learn this one day. Bringing your game out early isn't going to help you if it isn't ready for release. The initial bad impression that a half-finished game is leaving behind is very hard to overcome, even if you improve the game a lot later with patches. Even Electronic Arts learned that lesson, and says that for example Spore will be released when it's ready, and not before. In spite of MMORPGs being easier to patch than single-player games, releasing them only when they are ready is the better marketing strategy for them too.