I was skeptical at first, but yeah, it's pretty damn epic. I wonder how easy (or hard) it is to break the combo, though?
Fighter would break this at a few points with backstep.
Archer breaks it at the charged punch with AR, or at the stomp if the giant is slow.
Melee breaks at evasion with windmill, I suspect.
Mage... If they have fast cast, they can probably break with ice or lightning at the same points as archer.
Alchemist could probably stuff in a windbreak before stomp. Maybe. Otherwise I think they're boned.
Overall though, killer against mobs.