You quit by level 15, so you didn't actually play the game in any meaningful way nor you've seen any interesting and challenging content.
I know that every player on these boards is a superstar of MMOs and they can carry entire servers of bads to success by breathing on their keyboards while picking green gold from their noses and sipping cold vodka from a straw, but let's face reality, GW2 is actually challenging in certain places (not the whole game).
In Orr trash mobs will own you quickly if you overextend, veterans are a pain and champions mean death more often than not. This is reflected in many places all over the world: you can build, trait and gear appropriately in order to survive better, but you'll kill slower and this has drawbacks, as exemplified by most of the PvE dungeons.
It's true enough that there is little group interaction due to a lack of specific roles, which I miss dearly, but a coordinated group and a crappy group are miles apart and there is no denying about it, even if it's just boon management and debuff management. We're talking about doing a dungeon wing in 10-15 minutes vs not finishing it at all.
If there is one reason why I praise GW2 is their will to change the paradigm: interactive downed state instead of instant death, special class mechanics/abilities, weapons changing the hotbars, few hotkeys to manage with some thought behind their use (not true for all class/weapon combination sadly, some are done way better than others), self healing and no classes is kinda new and it's at least an experiment.
I add to that a beautiful world and a fuckton of places to discover (underwater tunnels leading to hidden caves, jumping puzzles, etc.) and interesting dungeons.
What I don't like? Lot of things: no healers/tanks, defiant/unshakable on bosses, currency purchased loot instead of dropped loot (on predictable loot tables in dungeons), some skills/traits/weapons being quite shitty for some classes, some classes being way too squishy, PvE dungeon content being berserker material only with a competent group or a pain in the ass with bad pugs and so on and so forth. There are no instanced raids and the open world ones are just zerg material. Loot progression is fundamentally unexistant, from the usual "raid for gear player" point of view.
There are also a load of little things class by class that imo should be reviewed in a timely manner, for example necros not having a cleaving melee weapon, but the list would get too long to be written here.
Its biggest shortcoming is certainly the lack of defined roles from my point of view, then the total lack of dungeon-dropped loot, then everything else I listed above.
This being said, I also can say that it's beatiful to see, animations are top notch, sync animation/effect is pretty much perfect, there is a good feeling when going melee and delivering big blows (for example the "oooomph" factor of the hammer weapon for guardians/warriors is amazing) and some combat mechanics for certain classes are really nice (e.g. engineer flamethrower, mesmer clone shattering, etc.).
I don't think it's the best MMO in the world, but it's certainly fun to play for a good while, I've been on it for one year and I'm still not bored. In Swtor, just to mention one, I didn't make it to the end of the free month.
