Aye, I play Vanguard. Yes it has the makings of a good game, but as Sony/Segal said at release they ran out of money and have to go live early. But they are patching bugs as time goes by. I would rate it harder in play than WoW, close to EQ2 in difficulty of playing classes, and a whole lot easier than playing EQ when that game first went live.
My AMD 3000+ PC ATi X800 struggled with the graphics, but it was playable in lowest rez. My new PC Intel duo E6600 and ATi x1950 runs it fine and it looks great.
PS RAM is a must, 1GB is ok, but 2GB is more realistic.