My first adventure in MMOs was World of Warcraft two years ago. After about a year, I realized that I had been grinding my life away for weeks on end and that the real fun of the game (raids, instances, etc.) were few and far between.
After that, I tried several other MMOs and was sorely disappointed. City of Heroes/Villains had a great tutorial, but after that I was left with a sea of identical grind quests. I love the character customization, and even the combat is decent, but I was lost very quickly with no help at all.
EVE Online was also neat, but within a week I was bored. I had to recreate my character twice because I was asked life-altering questions about race, class, and skills before I was given any information about what they meant. Exploring the various economic and skill systems was interesting, but the game hit rock bottom the first time I joined a corporation and realized I had paid to have a second job.
Lord of the Rings was great, but I found the world too large and players too spread apart. Adventuring by yourself gets boring after awhile. Otherwise, it was a very nice game.
Guild Wars -- I can't quite put my finger on what I didn't like. Other than the starting areas, there was nobody around, so groups were quite useless. The limited abilities and quests made things quickly repetitive. Overall, I just wasn't impressed.
I bought Age of Conan when it first came out and am pissed that I can't even give the game to somebody else at this point. Within only a few days of playing it, I realized I had wasted $60 on a terrible game, despite initial reviews being so positive.
Warhammer Online was great at low-levels, with public quests and RvR going a long way to encourage player interaction. Unfortunately, as I progressed I found I was all alone again, grinding my way through the levels. Too bad, because I thought it had a lot of potential.
Dungeons and Dragons was interesting and the action-element of combat was quite enjoyable. Even playing solo was quite interesting and I was constantly running into people while playing (finding a group wasn't often a problem). Again, community seemed to be quite weak, with hundreds of people just grinding instances to get the best items. The auction system is also completely broken: the exceedingly high minimum cost of items and the huge cut taken from sales meant that it was never worth it to try buying or selling an item, especially as a way to get above-average quality items as you were progressing. You would have better odds grinding for hours and waiting for the rare items to drop than trying to grind enough gold to buy them at auction. In it's favor, it was always to your advantage to team up with a group, so people did, which is more than I can say for most other MMOs I tried.
All in all, most games are suffering from poor developer support and poor community building. I think these two issues go hand-in-hand: the games don't lend themselves to player interaction. Most of them were difficult to find other people and to chat with them. Not a single one supported voice communication! Most also didn't have an emphasis on multiplayer; each player was out there for themselves and just happened to see other people running around. Because of these hurdles to communication, it was difficult to build relationships and the result was a lack of community. In the end, it was a single player game where the other characters running around may as well have been NPCs.
To make things worse, most of the MMOs were unimaginative grind-fests. I understand that part of progressing is accomplishing tasks, but "kill 10 beasts" and "collect 50 flowers" doesn't make for interesting gameplay. At least have a story, or new and interesting places and creatures, and especially some way for a player to leave a mark on the massive world they are a part of. It seems that MMOs are going the way of the FPS: stick the formula and sell as many units as you can.
If you ever do find a "good" MMO, I'd be happy to hear about it. I'd like nothing better than a game where I can make friends AND enjoying playing it at the same time.