Oh my god. 

You need to finish season 2 and then season 3. Jinora is the most broken bender of all time, she's so overpowered it's unbelievable. Oh, and Bolin kicks a TON of ass in the finale. 

And Lin gets much needed development.

And Tenzin.

Unfortunately Meelo and Ikki are on the backburner again, I don't really enjoy it but I don't mind Jinora either, they just made her unbelievably useful.