After having played for approx a week now, I can safely say the population is large enough to support gameplay thruout all the different levels. This was one area I was worried about in starting after the release of the expansion, but proved to be baseless.
Having just hit level 24, im flying thru the levels at a pace thats surprising. I knew the devs had updated the mechanics in leveling, but actually seeing it implemented is relieving. At the original launch, the leveling process was the main reason I walked away from the game at level 39, it proved to be too close to work. Now, its fun, and at a pace similar to other mmos.
Im almost at the point where pvp will start, so im looking forward to seeing it in its current state. At launch, you couldnt enter the pvp area without being killed within five minutes. It was horrible, no fun at all. And that sentence right there is a whole area of debate in the official threads, along with rifting. NC Soft is currently gathering player opinions on rifting by ingame surveys. And that is definitely a proactive approach.
Will update as I enter into the pvp arena and Fire Temple dungeon....