Book 2 ain't that bad. It does have a poor start where characters start regressing quite a bit(Poor Lin taking the brunt of it) and way too many storylines going on at once during certain episodes. But it improves a great deal after the Wan arc.
There are quite a few moments that I really like in the second half of Book 2 from the fantastic fight of Bolin protecting President Raiko, Bumi's accidental rescue and for as divisive as the finale is I still love that moment when
Korra walks into the Tree of Time and this starts playing. Beautiful stuff and a damned shame Nick still hasn't released the OST for it yet.
Flawed as it was I still got a lot of enjoyment out of Book 2.
Great work.