Well, regarding Korra regaining her bending, at the end she gave up her worldly attachments (in a very dark way; that shot down the cliff face was contemplating suicide). This corresponds to clearing her seventh chakra and gaining access to the Avatar State. It's not exactly unprecedented. More, I'd hardly call coming out the other side of that kind of absolute despair an experience that doesn't lead to growth or development.
Tenzin being recaptured was a bit weird, but I guess Amon did have planes, so. At least it doesn't contradict anything.
The situation with Tarrlok and Noatok seemed pretty easy to understand to me. Their crazy dad was obsessed with power and he passed that obsession down to his sons, even though they pretty much hated him. Tarrlok was set to attain it politically, only using his bloodbending in times of desperation, and the shock of the whole situation made him realize that despite his best efforts he'd turned out a lot like his old man. A shocking epiphany, a serious trauma, and a bit of remorse to make the slimy politician a more well-rounded character, and in his escape at the end he realizes the cycle's just going to repeat itself. Noatok, meanwhile, saw the removal of bending as the ultimate expression of power (he said as much), and went out in search of a way to use his own talents to achieve that power and impose it on the world. He manipulated the whole revolution as a means to that end. Two power-hungry brothers, neither a good guy, but not wholly monstrous either.
Anyway, I'm hopeful for a less urgent season 2.
