I would actually give it a 4.5 rating, but I don’t know how to do it. First things first, it’s wise not to compare this show with Avatar: the last airbender. Aang pretty much had just one goal in the animated series- defeating the fire lord and restoring balance. What happened after the series was more challenging than that. Dealing with a new world and fire nation colonies (which were older than Aang). So, i’d request people to read the comics.
Season 1- where non benders were against benders was nothing recent. People were against bending since Aang’s era, it only escalated when Korra arrived.
Season 2- meet the first avatar here and also, witness the destruction of all the previous avatars. People didn’t like it, but the end of the current avatar cycle was kinda evident. In ATLA- when aang visits one of the air temples (a room with statues of all previous avatars), they gave a hint that the avatar cycle was going to end and new era would begin. So, don’t be salty.
Season 3- I love the villains here. They were kinda right about their philosophies, but their approach was really extreme. A new air nation, Zuko and a lot pain.
Season 4- Now once again, people had mixed feelings. Please understand Korra was going through PTSD and was having a hard time. Her mind was against her.
Lastly, it’s a great show but a couple of parts were really unnecessary. Worth a watch (and a rewatch if you are into it).