I'm just going to launch into the things I like about it. Keep in the mind the only MMOs I've played a lot of are WoW and AOE:Online.
Character creation is a lot more elaborate than other games I've played. (I know that City of Heroes apparently had the best creation ever, but I never got around to that one.)
Personalized story arch. I love this so much. For the first 30 levels, the story arch is dependent upon your character and choices you made during character creation. There are splitting paths during each possible story as well, adding even more variety. There are little cutscenes in this game too, which I think is kind of cute more than anything, but certainly effective for the narrative.
Attacks and abilities change with weapons/attunements/kits. This is one of my favorite features by far. You don't just learn moves as you level, you have a different set of moves for each possible weapon configuration (as well as another set for underwater) that can be swapped out on the fly. Add dodging and lots of positional abilities and you've got yourself a game where you actually feel like you're fighting something and not just mashing number keys.
You level for everything except mob grinding. Well, you get experience for killing mobs, but it is probably the least efficient form of leveling. Quests, crafting, PvP, and crafting are all emphasized to be something you can jump into at any moment and feel "productive" as far as character progression goes. I think this freedom is the driving factor for why the game feels so fresh and new.
Dynamic quest events add a great sense of urgency to questing. It also brings every player in your vicinity together to do something epic together, which is just a better way to play.
Speaking on heading to town. For a small fee you can Fast Travel like a demon in this game. And you're even rewarded for finding the Waypoints. If there's somewhere you want to go, you just go there. No travel time.
It's new. And by that I mean that everyone is still figuring it out to some degree and there aren't many elitists yet. As someone who plays a lot of WoW, I find that extremely refreshing. Sure, the game's got a billion bugs, but if someone pops into the area chat and says "Good grief, why can't I find X" or "This game seems hard, can I get some pointers?" people actually help them instead of just calling them a noob and telling them to go to a website. With the exception of last Friday night when a very strange (and uninformed) political debate broke out in the zone I was questing, the chat has stayed 100% relevant to the game and is almost always positive.
No subscription fee! Just buy it already! I'm on the Dragonbrand realm.
P.S. I should probably mention things I dislike too. I didn't really think of that. If I have to pick something I do not like, I would say it's that you don't get your first 5-man dungeon experience until level 30 and it's fairly difficult. Dungeons are my favorite thing about WoW, so having to wait so long for each class stinks.
P.P.S. There's 10 professions (or classes) but only 5 character slots. What's up with that?