It makes sense Don has the most open-ended ending of any of the characters tho while everyone else is off getting these neat-bow endings. Only Joan/Betty get sort of shafted in the end.
But if y'all wanna take the whole "Don made the ad/went back to NY to work and be close to his kids/ is it at peace" angle, one can also say he still made the great ad, but also still reverted to being a mostly absent father, and still ended up miserable.
There just wasn't enough there for me in the last 5 minutes to imply more than, "yeah he got over THIS hump, and he made another great ad". He still hasn't seemed to gotten over the real hump of the show of finding who he is. A smile doesn't prove anything.
Weiner has stated he believes people don't change, and while its natural to hope for the best and lots of the final wrap ups are super rosey, it's very easy to see how a theoretical Season 8 of Mad Men could unravel every happy situation presented in these final episodes, and based on how these characters have acted so far, there is little reason to believe these scenarios will play out any differently.
It's just sort of annoying because at least you expected Don to change and for the show to show it by having him you know not go back into the vortex of work, ego, and sex that was his job but it's implied he goes back to McCann, back to square one.
Everyone else, well mostly, Roger is still a manchild, actually evolve but Don is practically the same dude character-wise from "Smoke Gets In Your Eyes". He seems to have learned nothing.