I think the level progression is fine. I know you say you're not rushing, but just because people are 50 now doesn't mean that you're not also rushing, just not quite as quickly. Like you said, with this game (for now) it's about the journey, not the destination. Going at a comfortable pace for me I can get to 20 in a week and I think that's fine, maybe a bit too quick even. The game is brand new so there isn't a whole heck of a lot out there for the level cap yet. Why rush? Might as well wait for the content to catch up a bit, otherwise you'll end up bored a month later.