The more I think about Aetherling, the more I like him. He seems interesting in all the right ways, and powerful, but not in a dominating, unfun way. I mean, right off the bat, you get to make a decision when casting him: as soon as you hit 6 mana, or wait until you reach 7?
He's not the greatest blocker in the world, and you need to make sure you can afford his monthly installments, but I think he's a lot less boring than something like Sphinx of Jwar Isle. Hey, you might not attack for 8 unblocked damage every turn - you might only crash in for the 4, and then blink him out so he can play some D. I like that he's a versatile switch-hitter that can do a couple of things well.
And hey, he's got to be better than Thornling. Right?
Frost Titan has been really good for us in our cube. Even as the runt of the Titan family, he has a pretty game-changing effect when he hits the table. It's not insignificant that in a Titan-on-Titan battle, he almost always comes out ahead.