Alright, I'll bite. I think the entire series of Korra is vastly inferior to TLA, with the possible exception of s3. I'd write an entire post on it but I think this guy sums up why Korra s1 and s2 were shit: http://scepticalprophet.wordpress.com/2012/07/13/why-avatar-legend-of-korra-was-bad/ .
The post in the above is mainly concerned with the plot and character problems in s1. They are even more pronounced in s2 imo, especially with the absolutely absurd miracle ending. Another thing that repeatedly irks me about the series is the lack of consistency regarding bending talent. Bending in TLA was a rare thing and a big deal. Aang didn't magically get better from episode to episode, he actually took 3 seasons (65 episodes) to get his bending better. Korra? She takes to metal bending immediately upon being introduced to it. The villains are no better -- Zaheer is some airbending prodigy able to keep up with Avatar state Korra, and Kuvira had honed her talent for probably 10 years? yet she is able to go even with White Lotus trained Korra. And those villains in season 3, those ones who were super elite? Taken down by Mako and Bolin, because fuck logic. The bending across the seasons never felt like an ancient discipline that required time and effort to hone -- instead, it increasingly degraded to just throwing elements at each other, because everyone is apparently at the same bending level.
And don't get me started on Korra. Oh my god, the whiny MCs are the worst, and Korra is up there for least favorite MCs of all time. Don't get me wrong -- Aang was a bitch at times -- but at most we would get one episode of comedy for his issues. And at least when it matters most he stepped up. Korra? She requires at least 7 episodes of healing, suffering from some PTSD that is miraculously (see how often this show uses this??) cured. Even when fighting the villains, not once does she win by herself. It's always with the assistance of others. Always.
My takeaway from Korra is that most of the series was awful with some odd bright spots. The Avatar Wan episodes in s2. The entirety of s3. Toph and Varrick in s4. However, as for the rest of the series...I honestly wish I could forget it because it taints my impression of the original TLA, a show that will forever be my #1.