I've been actively following its development since its start. It's designed and developed by Funcom, makers of Anarchy Online which I've played a lot, so that's how I know about AoC.
It has some awesome features, and a different take at combat and magic than any of the current commercial mmo's which are just point and click. Age of Conan isn't.
It will also have formation combat, horseback combat, huge sieges on both npc villages and guild held battlekeeps and lots of other nifty stuff like crafting and drunken brawling. I'll be trying it out for sure, and if it's any good, I'll stick with it.