With my main a lvl60 after about 2/3 weeks of playing I can only comment from the perspective of a noob.
I do however have some experience with the various startingzones, both old and new and I'm very much impressed by at least the Troll startingzone (should do a gnome and an undead one soon since that's said to have changed a lot as well).
My alt just finished Darkshore and that is also very engaging and I did Northern Stonetallon with my main (about 20 lvls too high) and it was extremely fun!

So not only are the new-lvl experiences much more smooth, it's also very funny and introduces new ways of interacting with NPC's which is very interesting and makes you wanna stick with a specific questline much more than before.
Also the variation in the types of quests that is offered combined with phasing is an improvement I very much enjoy.