exept this 15 level is far from enough, i'm sorry but some class (and i talk of class only) need far more level for be mastered or even understand.
a good example it's some gladiator i have run into that wasn't using the right combo: Fast Blade > Savage Blade, but instead was using: Fast Blade > Riot Blade. worst was barely using him flash.
i have many example of player around 20-30 (even some at 50) that was barely knowing the basic of them class and was simply wrong how use them skill. and we are not talking of efficiency, but really the basic. (like the white mage using cleric stance... and was fully equiped in intelligence)
from the video we did seen of the ninja, we can notice that the sign must be enter in a certain order, when you launch the skill, all the sign have the same GCD, leading if you miss your sign order you will loose your skill, worst you need to do this while taking in account your position as melee and the other CD, probably combo too...
me i'm happy to see a class/jobs that will ask a bit more of skill for be player, but do a new player will be able to play it correctly without a minimum of experience i'm not sure!

ps: the video it's there http://www.youtube.com/watch?annotat...&v=ppn5aGLfxSk