They call it not only a new zone named TASUQ but even a new chapter. Why so? Nobody knows. Yet.
Facts are: Level cap increased to lvl 98 (wow!), a new zone which has enough quests to reach cap on 2 classes and a new instance. The k/s and s/k combos got nerfed too, it seems.
You might want to read all official stuff about it. Or not.
Furthermore, you can do the Colourweave Festival now and of course our famous Ane has her guide on anpedia.
Have fun and enjoy 🙂