I really can't see what's so exciting in this video. I will ignore clunky animations.
500 skills, so what? You would get the same effect if you combined skills of all classes in WoW, and then pick from those.
Unique builds? It's obvious that a month or 2 after release you will have a set of cookie cutter builds for certain purposes. They won't be able to balance them all. In fact I wouldn't be surprised if those synergies defined a "class". Master of stuns, master long range combat, master of curses, master of healing and so on...
In the end there will be a list of builds to use on specific bosses / instances / quests or whatever. And suddenly you will notice that you have 5-10 "classes" left. Players will visit pages about builds and spec this and that for particular situation. Probably all in the same way, at the same time.
I haven't seen anything revolutionary in combat in this video. You select monster and start using skills from your action bar. Some skills have synergies with each other, just like most skills and talents in one spec in WoW have.