Q u o t e: I played the monk 4 times. The "invincibility" thing is really no big deal, because even though you can't be hit for something 2.3 seconds, you'll more than likely re-appear smack dab in the middle of a crowd. If you're worried about it being used to dodge attacks, consider that A: it already has a teleport effect, and B: the monk also has impenetrable defense that also makes you invulnerable.
That's exactly my point. It'd be senseless if you could use this move (even twice in a row) for 4 seconds of invulnerability while performing 14 attacks. Imagine how imbalanced that would be in PVP? I'm not saying it's already a problem, but that it's just something the development team needs to take into consideration. Someone related SSS to omnislash from DOTA's Yunero/Juggernaut (though the move is originally from FF7), and that's exacly what it looks like to me - consecutive attacks on random multiple targets or a single target, with temporary invulnerability.
This differs from the skill we're all familiar with that also makes you lose control of your character - whirlwind, since the Barb can still be hit while performing the move.