I have the opposite problem. My friends all play and I'm trying to force myself to like it. But as far as other games I've played, it's really lacking.
I notice a distint cookie cutter feeling about everything.
Your upgrade path is very linear and VERY limited.
There aren't many classes or races.
The meaningless quests get a bit tiresome. IE: Talk to bob, bring him this sandwich.. "wtf.. you must be kidding me, he's right across the street!"
And then you have the level treadmill of it all.
I play on a pvp server right now "bleeding hollow", and pvp serves no purpose. I can kill or be killed all day long and gain or lose nothing except my free time. For that matter, there's no penalty for death whatsoever by mobs and humans a like?
The bottom line is that I think this game has flared up in popularity so quickly because it's easy. You're forced to only use specific weapons and armor, everyone gets the same quests, and no penalties for death or pvp loss.
Just my $00.02