As with all adaptations from animated to live action, it's nearly impossible to capture the quirkiness of the original animated series because alot of the feeling and warmth from the original comes from the possibilities that animation brings. For example the anime-esque facial expressions when something goes wrong or explosive dialogue coupled with bouncing physicality is impossible to mimmick with a human face in live action. The dynamic of the trio is rigid and the acting is not very believable. They will suddenly have an argument about something and it gets heated but there was zero real motivation for the argument so it feels unjustified and hollow. The effects and fight sequences are actually for the most part great. The dynamic between zuko and his uncle are good. I think If you are 13 or 14 and have never watched the animated series then this will appeal to you and you will enjoy it. It's not going to satisfy hardcore Avatar:TLAB fans. It's so difficult to do what they did and I think it's way better than Shayamalans film. It has however a smooth watchable vibe and moves at a pace.
Edit: I now know what it reminds me of. It's similar to those old series in the 90s like Hercules the legendary journeys or Xena Warrior princess. That is why I somehow like it. I want to emphasize the easy watching and colorful energy dispite the above negative things I have previously mentioned. They seem to toggle fun themes in such a way that it's good to watch none the less.