I think Spirit Bending is awesome and a great idea.....cuz it looks like it takes alot of energy so it seems to be pretty dificult....i dont think its cheap.....its awesome.....what do you think? and do you think he was the first one to do it???? probably not....cuz there's a part in The Library episode where they look in a book that has a pic of someone who looks like a fire nation avatar walking up to a lion turtle...its basically a hint for the finale.....so ya....hey! maybe it was Roku who was in the picture!!!...idk...he probably would've told Aang...

Aang wasnt the first to spirit bend, like Deus Ex Machina-....I mean the Lion-Turtle said, before the Avatars, people bended the energy within themselves.

I think it was somewhat of a cop-out on the part of the creators and I personally would have preferred an old fashioned attack to take down Firelord Ozai, as far as the battle goes. As for the plot, it was interesting that Ozai lost his bending because it was almost like a fate worse than death.