My take on the Korrasami ending is that the creators certainly INTENDED for it to be a romantic ending. So the relationship is canon. But the build up to it is lacking. Writing letters and compliments on hair do not a relationship make. I've got a best friend I could talk to for hours. When he starts doing a random jig in the middle of a room, I have no problem going up there and dancing right by him. No other person, man or woman, in the world would I do that with. However, neither of us is gay. It's just what being best friends is about. Korra and Asami having a romantic relationship feels forced because there's been little build up and what little there has been is indistinguishable from close friendship.
I chalk it up as the creators doing their best within the restrictions set on them. After all of the bull shit Nickelodeon has forced on them for LoK's run, no fucking way were they going to get the greenlight for a lesbian romance in a mainstream kid's show. I don't hold that against them. I think that ending moment was beautiful. But it isn't all that it should be, and that's a shame.
The rest of the ending is great. Everybody has moments, General Iroh finally shows up again even if he is dreadfully underutilized, Hobo Guy shows up and is WONDERFULLY utilized, the animation, visuals, and sound were all wonderful. A great cap to a great series. The series isn't for everyone, but I can appreciate it. I don't know if its better than The Last Airbender, but I love it more. TLA always felt like rather standard Saturday cartoon fare. Stunningly executed, but still just standard. TLA aimed to be more thoughtful, more emotional. It didn't always work, but I appreciate the effort, and when it does work it shines like no other cartoon I can think of, except maybe for the episode "Code of Hero" in Beast Wars.