Fun for what it is.
GW is a game that, in all honesty, focuses on Guild v. Guild and PvP play, that isn't to say the PvE aspect is horrible, far from it in fact. It's just that, for people like me who aren't big on MMORPG's to begin with, doing the same thing twice (even with different character classes) is boring. In reality the PvE play is really a means to an end, the end being PVP and GVG battles. the entire purpose for doing PvE is simply to unlock new items for your PvP/GvG character to use.
Even exploring the world is pointless as there is no real reward for finding new areas or even finding new creatures (if you've seen them in an earlier area of a certain section of the map, you'll see them everywhere in that section so there really aren't any new creatures to find)
As for the creatures, they are all ,for the most part, variations on theme. the only exception to this would be the showcase creatures like The Forgotten , the stone summit dwarves, the Enchanted armors, the Undead and the Charr.
But even these tend to be clones of themselves.
The only real reason I can recommend this game is because it's free to play online, but even that bit of enticement grows thin after doing the same quests and mission repeatedly (yes there are different character classes, but all the missions and quests are pretty much the same for each, even in the early "pre-searing" stage of the game).