Well, I've played it a bit.
My first impressions are that I like it a lot more than Guild Wars. And really, it isn't all that similar to it. Haven't played Lineage II so I don't know about that.
I don't see why it's a problem if you're not the most powerful. It's not like you're hanging out with people 20 times your level or something. The point of the game is not to be the most powerful guy. At least not for me. I just have fun partying up and going to kill stuff, the leveling stuff is just a path to new content really.