A pseudo-Varian Wrynn? Interesting, but the Battlecries probably don't work. Potentially great if you get him out of an Ancient Harbinger and get lucky enough to pull out Deathrattle minions so you can play N'Zoth down the line; maybe means you have to mulligan for N'Zoth to have him out of your deck in a Y'Shaarj + N'Zoth deck. Very interesting stuff...
EDIT: Whoops, I thought Ancient Harbinger put the card into the battlefield. Regardless, both have some great potential.
On average this is not has good as Varian but at the same time you don't commit has much, while Varian offers more stats in your ideal situation Y'Shaarj is more consistent and less vulnerable to board clears.
They both suffer from the problem that while being a 10 drop they don't "seal" the game.
Varian Wrynn has better potential for great things to happen, this is (a LOT) more reliable to do what you want it to do. Neither is better or worse than the other, really. This will see more play simply because more classes can use it.
Let's say you make a control hunter, for example. A bunch of control tools, minions that are created by spells (hunter is great at that) And this + Ysera + Ragnaros the Firelord.
That's a good finisher in a spell heavy deck. In a way, it's also a more reliable (and beefy!) Aviana.