Pros:
Korra having to learn from each villain's motivations and moving on from them is a brilliant idea and is one of the best written parts in the entire series that helps her grow as a character (but hopefully doesn't complete her character arc since the Season isn't over yet). That's coming from me of all people.
Showing more of Korra's psychological weaknesses is a plus.
(Personal Pro) The Nostalgia Critic said that Seasons 3 and 4 work as an apology for Seasons 1 and 2. If this is true, and they are listening to criticism, then this is great.
Cons:
The airbender kids' antics are really annoying in this episode and I really don't see the point in having them in this episode. Why is this here? Gee I dunno, maybe because it takes up MOST OF THE EPISODE.
(Personal Con) Is it me, or does Jinora's voice sound weird?
The conflict between the airbender kids is very cliche.
Overall:
Critically, this is easily the weakest episode in the series. But ironically, its one of my favorite episodes next to "Original Airbenders" of Season 3.
The way they connected the three villains of the previous series and how Korra needs to develop from it is beautifully written and some of the best writing I have ever seen in this series. This is coming from ME. The guy who continues to criticise this series regardless of what people think of me.
Oh and showing some more of Korra's psychological weaknesses is always a plus.
Why is this the weakest episode? Because of three flaws.
The airbender kids. UGH. Their antics take up most of the screentime when I just want to see some freaking development for Korra. If you thought the Earth King was bad, wait until you see these guys. Their conflict between each other is hopelessly cliche that I cannot believe that the writers ran with this plot. Seriously? I'm sick and tired of seeing the typical "men need to hunt", or "the middle sibling or younger wants to get involved but can't because the other siblings are stuck-up idiots", and the "getting caught by the enemy and the siblings have to bail them out" cliche. Ugh. UGH.
Plus Jinora has a weird voice. Enjoy.
Overall, this episode has some truly great writing that connects the three villains of the previous seasons (It's like they granted my wish!) but is one of the weakest episodes due to having some truly cliche and boring moments throughout most of the episode.
Sigh....I'm going to move on to episode 5 now. Wish me luck....