One thing is sure, leveling in this game is fun. Maybe it's not THAT revolutionary as it is advertised, but the difference is still big enough to notice. Every other MMO I've played made me cringe whenever I had to level up a new toon. But in this game I just don't mind, It's really fun to just bounce around the zones, doing an event here, filling few hearts there and getting solid XP for things like gathering, crafting or just exploring. I'm finally leveling up in peace without the feeling that "OMG I'm in this zone 5min longer than I should and I've just wasted my time".
Unfortunately there is a bad side. Scaling doesn't work - or at least, it's not tuned yet. The idea behind scaling down level of a player was to make sure all the content is challenging and to prevent higher level players coming over to lowbie zones and one shotting everything and destroying (kinda) fun for still leveling players. It's just doesn't work that way.
I've started a new character(warrior, last bwe I've played engineer) this BWE and got him to 37level. So at 35lvl I've went to 15-25 zone and.. could one shot everything. Veterans didn't have chance either, 5->F1->SignetofMight->2->dead, as for champions had to throw in some regular attacks. Not even once, I was in danger no matter how many mobs I was pulling. As for 1-15 zones, I was killing monsters by looking at them :/.
Another "broken" thing was XP system. Thing is, this game gives you XP for everything - and that's good, cause you don't feel that you're wasting time crafting in the city or just running around the zone and taking pretty pictures. But.. XP boosters are an over kill. I went from 25 to 30 in just a bit over an hour. How? The 1hour 50% more XP booster stacks with extra 100% XP killing streak one (you have 30s to kill another monster before it wears off). Went to one of those mines with "mole people" where spawn rate is insane and there is that event which is repeating very often (every 5-8min or so) that's it :/. At 30lvl, went to AC and got almost 2 levels out of it.
After that I went to the city since I wanted to max out my armor crafting, got it to 190+, but had to stop since I couldn't get the reagents from +40lvl zones . Then I realized.. I'm 35 lvl :/, 3 levels in less than an hour for running between anvil and trading post. I dunno man...
The XP gain in this game should be toned down a bit, you are very quickly in a position where you can overpower whole zone after just entering it and since scaling down doesn't work it takes some fun out of it. The XP boosters shouldn't stack either or we may have 80lvl people running around, one shotting everything just few hours after launch. Or just remove the killing streak one completely, it's such an over kill..
I really, REALLY love this game, but they have still have so much left to tune...