I can't stop playing...
I'm onto 1-2 now. So I would guess about half-way through the game. I'm at soul level 34, and I'm feeling decently powerful now. I was playing some last night, and was invaded 3 times, and I owned all of them, it was pretty awesome. I felt like a bad ass. Granted, one of them, got half his life taken away by a dragon, and then I just finished him off. I haven't really tried co-op or invading anyone's game yet. I actually don't even know what the benefits to doing that are, but damn it's fun, and it adds a certain amount of intensity to the game.
This is seriously one of the best RPGs I've played in years. It's so addicting. And I love the way the maps and worlds are set up.