This would be totally fine if all the classes had neat, fluff-inspired names. Having some that do and some that don't is not only a little jarring, but actually dissuades people from picking the classes with the archetypal names. Classes like Mesmer and Paragon just sound special. Yes, this is totally a pet peeve of mine rather than a real grievance, but when it comes to class balance, especially in an MMO, consistency is God, and the naming conventions of the classes need to be part of that consistency, or the game world suffers for it.
GW just strikes me as being phoned in. I really did want to like it, but every time I tried to play it, I just got underwhelmed and bored within the hour and had to go play another game for a few days to get the taste out of my mouth. I hope GW2 is good, but honestly, by then The Agency and Champions Online should already be out, and both of those games look far better than what GW2 has to offer so far.
The names are entirely unique, instead of pulling stuff from a hat, why not actually read the names in full:
Mesmerizer: Pretty much describes the class. You have spells to take control of your targets and and punish them with great force.
Paragon: Someone who inspires; Idol, the main gameplay element of Paragons are being able to buff others while having a decent amount of power to keep yourself good to go. Exactly.
Assassin: Quick, massive AoE/Single target damage, but fragile. Exactly.
Warrior: Instead of having a million different classes that should be just one (I'm looking at you, WoW). GW aces that, Axe Mastery, Sword Mastery, Tactics, Strength and Hammer Mastery, that's Paladin, Hunter and Warrior right there.
Ranger: Weeeelll, I shouldn't have to describe this one....
Elementalist: Controls elements. Not only good in three ways (Buff, AoE and single target), but great combined with almost any other class.
Dervish: This class's focal point is using the god's power to bring down heavy amounts of wrath upon their enemies. They also wear traditional dervish skirts..
Necromancer: OK, I really shouldn't have to describe this one.
Monk: I really like this because it differs from your typical Monk class. Not only can a single (well balanced) monk manage seven other party members, they can also take on enemies en mass, a 55 Monk (AKA invincible Monk) can take on the UW solo, which is hard for most other classes to do it as well as the Monk can.
Ritualist: Rits are commonly know as ANets forgotten child, so yeah. Not much to see here other than insanely powerful buffs and great healing (in some cases better than a monk). OK, so this class really focuses on either sacrificing their health or minions to summon shit. Rituals in the rawest meaning.
Of course guild wars isn't diverse with a class roster like that...you need three copies of a single class and the most generically vague names to make a great game. Pft...
Everybody hopes GW2 is going to be better; don't get your hopes up. Aside from the armor (which is awesome), EotN is a massive grindfest, and is supposedly "just a taste of what GW2 will be like"
While I agree that both the games have their flaws, GW is much better developed. It doesn't seem like they're pumping out more and more content just to get that extra 120M a month. It seems more like an honest attempt at an MMORPG than WoW is.