People keep saying that due to their age, that Aang and Katara shouldnt have gotten together, that their is no way she would be romantically involved with a younger less mature person. The writers of this show did end up making this the Zuko and Katara show, considering their characters over the show developed the most, but having the two be together would have sucked. Aang accepted his responsibilities as Avatar, the responsibilities to protect his world and bring balance, his way. Not the way the Avatars in the past had done it, but his own way. The show was sending a message of follow your own path.
I truly loved the ending, Aang didnt force it upon Katara, she came to him and showed that no what the war was over, they could all move on with their lives.
Besides after they showed that Zuko had a girlfriend a while back, I completely gave up on the idea of Zuko and Katara getting together. The only for that to work would be if Aang died in the last episode sacrificing his life for the land. True it is unrealistic that a young boy in the end gets together with his first crush and everyone lives happily every after, but so is a six legged flying bison.
Im not gonna complain about the ending, it was cute and fulfilling. I just wish they would show where Zuko's mom is.