There are so many changes in this live action. Nobody was expecting a copy and paste but there are only a few things that are the same as the cartoon. The amount of changes they made outnumber the things that stayed the same. Spoiler warning for anyone who hasn't watched or finished the show...
Katara, Aang and Sokka have no chemistry whatsoever. Most of the acting in this show is bad. The personalities of the main characters have been changed so they don't feel like the characters they're supposed to be playing. Some of the visuals are nice but there's a lot that I can't help but think they could've don't a better job at making that look convincing. I understand it's only 8 episodes but the entire season feels so rushed because they put too many storyline into the episodes. I've got no problem combining storyline if it's done correctly but katara and sokka in the cave of two lovers? This isn't game of thrones. It's not the cave of "love in general" it's the cave of two lovers. The whole point is that it was romantic love that helped you find your way through the cave so having siblings in there is just weird. Also the badgermoles they encounter, they don't see with emotions like love they see with earthbending. Also bumi was the complete opposite in the live action. In the cartoon he was happy to see Aang and in the end of the episode had a good lesson to teach Aang. In the live-action bumi is bitter and resents aang and aang is the one to teach that lesson to bumi. When aang goes into the avatar state after that forest gets burnt down to find the missing people from the village he takes sokka and katara with him into the spirit world. It wasn't a bad change except aang was supposed to meet rokus dragon and that didn't happen. By the time they get to the north pole aang hasn't even attempted to try and water bend. In the cartoon he has a little experience at that point but in the live action aang lacks motivation to learn the other forms of bending.
In the cartoon when aang finds gyatso you can see that he took down a ton of firebenders before he died and in the live action they don't show that. When aang gets captured at the southern water tribe by zuko and gets saved by katara and sokka later on aang triggers the avatar state and damages zukos ship but that doesn't happen in the live action either. Another thing is that cartoon aang was at least aware of the "avatar state" while live action aang has absolutely no idea in the beginning what his abilities are. I understood going in that there would be some changes but literally everything is different. There are very few things that stayed the same and I'm honestly surprised that so many people are ok with the massive amounts of changes. I'm ok with change if its just as good or better than the original but this much change is ridiculous and it wasn't even good change. The costumes look like cosplay but I got over it in time. Also I understood the blending of different stories into one episode because the season only has 8 episodes... and I was honestly ok with the idea of blending people's stories together until they started introducing things from season 2. Season 1 has 20 episodes worth of material to get inspiration from and you decide to take things from season two??? Anyways, I know this is a long review and I apologize. This is just how I feel about the show.