A few thoughts:
I liked the ending, though not until the next morning when, while recouting the details to Mrs. Phi, I finally caught the connection between Don's meditative Cheshire cat-grin and the Coke commercial. Until then, Don's retreat with Stepanie into a hippie commune and his crisis of conscience didn't make any sense, from his tear-stained phone call with Peggy to his apparent moment of empathy with a proto- cubicle drone. "I took another man's name . . . and made nothing of it." No, he made "Don Draper" into the most sought-after creative name on Madison Avenue; finding the limits to the happiness and meaning that accompany his fame is not the same thing. And as for the drone's lament at being invisible, replaceable, expendable: Don was the opposite of those things from the beginning, drawing the envy of every man he met and the loins of every woman. Yes, he alienated all his personal relationships by failing to control his zipper, but again, that's not the same thing.* But who cares? It was all an artifice to put Don in a place to Ommm his way into advertising history.
I'm happy for Pete and Trudy. I was so afraid last episode that their reconciliation would fall apart just to spite those of us rooting for it. But apparently his million dollar signing bonus and Lear jet finally succeeded in providing him with the status he craved. That doesn't make him a good person, but it does make him relatable: I've always said that the little weasel was the one character whose motivations I really identified with. Pete should have been the one to hug cube-drone-man.
Joan's character arc was absurd. She began the series as the ultimate alpha female who deployed her icy sexuality to keep the men around her awed and at bay; she ended it mewling about the EEOC and Betty Friedan. She began it openly scornful of Peggy's career ambitions, preferring to serve as Roger's mistress; she ended it trading in her rich and retired lover for . . . gambling her cashed-out partnership on starting a production company?**
Given creator Matthew Weiner's well-documented ethnic animosities, it's probably for the best that he didn't consider Christianity to be interesting enough for any treatment beyond the occasional drive-by shooting. But the rise of Evangelical Christianity in the 60s and 70s has been a more significant and enduring manifestation of the counterculture than the "hippies" ever were. It's too bad that the show lacked the perspicacity to give this a fair treatment.
* Also something about not recognizing that people around him loved him, which may have been what Don was actually empathizing with. This is marginally more credible, but only just, since I don't really think this was the source of Don's problem.
** The only more absurd character was Harry Crane, whose misfortune was to be the dumping ground for every contrivance the writer's need to dig themselves out of a hole. He began as, by the standards of Sterling Cooper, a straight arrow; he ended by first hitting on and then half-assed blackmailing Megan Draper.