Nope, not it.
Not it either.
There we go.
Their chassis, compared to the Hezrou's, has better ability scores, natural weapons, and movement modes. The hezrou enjoys superior AC and SR, though.
Dance of Ruin is nearly completely useless; I shouldn't have to explain why. Spending 9 rounds of actions on what a moderately skilled blaster can do in one or two is not impressive.
Spores is more interesting, as it's a free action to use, can't be blocked easily, and will take at least an action to negate. If nothing else, it makes for nice nova-topping.
Stunning Screech can be very useful: giving everyone a bonus round is generally a good thing. However, it should be remembered that a vrock will typically be the party's primary damage dealers. A round of stunned enemies isn't that useful if no one can do anything useful with it. Furthermore, it should be noted that immunity to stunning isn't exactly uncommon at higher levels.
A vrock's summon ability is about equal to other demons. Dretches are pseudo-useful: another vrock is great but unlikely.
Finally, the SLA's: Heroism is laughably weak (1/day: Seriously?) and I doubt telekinesis will ever be really helpful (whether in or out of combat), but Greater Teleport is always great and Mirror Image is a good self-buff.
All things taken into consideration, vrocks deserve a LA of +1, being roughly equivalent to the hezrou.