it's trying a little bit to be Avatar, sure… and to that end I think its more hampered by being a nostalgia property than anything else. The NEED to include a whole bunch of elemental princesses never really worked for the show, and even after five seasons I still don't care about a single one of them... but the villain stuff where they're allowed to do actual story and character work is pretty decent. I like all the villains, they get the actual character growth and plots you don't quite know the full arc to.
The heroes are all pretty dull. You might personally like Mermista or something, but there's not a lot there and none of them are any different than from the first episode they appeared. Heck, I think Netossa and Spinnerella have had like five lines of dialogue between them in the entire series.
So when the show is doing its Zuko portion it works. Not so much when its doing its Aang part.
And its really more like Sonic SatAM in structure but the leads don't feel as diverse personality-wise as that show managed.