Well I never played GW1. Only got into MMORPG's not that long ago (a couple of years maybe) and I was never willing to pay for one. However, GW2 seems very good and I would gladly pay for it. The only thing that annoys me is ones where you have to pay monthly, since I don't play them all the time it would be a waste of money for me, that's what I like about GW2, because it's a 1-time buy and play when you like.
Also, i've heard that half of GW2 is set underwater, so you have your set of skills, then these skills will slightly, if not completely, change to compensate for being underwater. You also get a helmet which allows you to breath underwater (so it doesn't make underwater battles tedious because you have to keep popping up to get air). This is quite and interesting innovation, and if they pull it off, it will do very well.
Looking forward to it, just gotta get the money.
^ Pro review FTW