I'd probably say the biggest selling point is the combat, which is, well let me pull the official explanation:
Brutal Physics - Blood spurts from enemies, right where your twin blades sliced. Enemies fall, only to become corpses you can hoist and brandish as sadistic weapons. Watch as walls crumble and whole buildings topple, providing you with new toys in the battlefield. With Source Engine physics and destructible, interactive environments, Vindictus redefines everything you thought you thought you knew about "free-to-play"
You can choose to use the keyboard (WASD) setup we're all used too, or just the keyboard and the mouse as a camera aid, but I went for the usual MMO style so you have your attacks on your mouse and that worked really well. You can build up combos and, depending on your class (although there's only 3 been released so far in the European version of the game) unleash special attacks and finishing moves. It really is a blast.
I've picked a Tank class and after completing the introduction I'm now questing and running dungeons to hopefully pick up some better equipment as there's some very cool looking gear in this game too.
This clip shows off a few things. The graphics of the game, which incidentally are created using the Source engine (CS:S anyone?), one of the more range focussed chars, who also has a giant scythe and a look at some of the baddies you can expect to be fighting on your own or with a party.
For more info see the official site (EU).