For the million time, Guild Wars was NOT a MMORPG; it was an Online CRPG. The difference being an instanced private areas for the player's party and of course, hub-like cities/outpost throughout the game world. (Note: The developers themselves said such a thing, yet somehow GW is classified as a MMO, which I'll leave it at that in my 'rant').
Guild Wars was a PvP-oriented game, as simple as that, the PvE aspect of the game contained huge amount of grinding, hidden behind ranks and achievements to unlock certain PvE-only abilities, which completely ruined the major gameplay feature I enjoyed about it, team builds (or rather, group of 8 players with 8 specific skills to form a force to reckon with that most of the time was put together by rather bright people). Somehow, this aspect was completely destroyed by 'elite' PvE abilities which literally turned a challenging PvE encounter, into a walk in the park.
What I like about MMOs, is the immense and 'life-time' replay value, which of course some like to call end-game. Getting the best gear to vanquish your foes or face greater challenges. A game that rewards, dedicated players, not just those impatient players who want everything given to them, which the player working to earn it.
MMOs biggest issue is the support of the developers, one good example would be Age of Conan. A game with so much potential, an amazing world (Hyboria), an amazing back story and impressive technology to render Hyboria as it should have been. Funcom took at least 4 months to remove all the game breaking glitches, exploit and bugs. Not to mention the major changes to balance the core game play itself. Based on the state of the game, when I unsubscribed, there is a lot of work to be done by Funcom. It just shows that the player need to spend quite a lot of money, and time, and also be able to bare with the support of the game (which is both a good and bad thing in the long run).
On a final note, I do love MMOs. Although I wished there was a little bit more done to change the turn-base aspect of the game, and really work on other settings than the fantasy base we are getting with majority of the MMOs released.