I loved it. I didn't think it was safe either.
I thought that the finale showed both character growth and permanence of characteristics. People change, but they don't change the core of who they are. They evolve it, instead. And to me, that was pretty much the entire finale and the last season. Consider the major players.
Pete
Pete had, for pretty much the entire run of the series, been a guy who always wanted more and was never satisfied with what he had, even when what he had was what he had just wanted. This last season, though, Pete basically had a mid-life crisis and realized that forever chasing the next brass ring holds no purpose to it. Moreover, he realized he'd wasted the one thing that really could've made him happy. His reunion with his wife and daughter, and his success at Learjet allowed him to evolve. He's still a stiff blueblood and will always be that, but at least he'd finally let go of the things that had driven him -- to misery, I should add -- in the past.
Joan
Joan changed in, I think, two really, really important ways. And they're ways that, I think, people might otherwise miss. In the past, Joan had basically tied herself to men who could provide her with a better life. Men she loved, yes, but still men who could help her life. Roger, her doctor husband, the guy she met this season, they all fit a general profile of a successful or upwardly mobile person who can basically give her the kind of life she wants. But the thing is, with this last guy (whose name eludes me), she realized that the life she wanted was one of equal partnership where she could determine her own path. Rather than be tied down to this man, she chose professional success. Now, granted, her hands were somewhat freed by Roger's revision to his will. And that brings us to the second major change. Joan had, especially in this season, felt trapped by her life. She had obligations to her son to provide for him, and she needed to make money to do that. Roger's will revision, naming her son as a beneficiary, changes all of that. But here's the really, really interesting thing: instead of it freeing her to live a life of luxury with her rich new boyfriend, it frees her to pursue personal professional satisfaction. She can take a risk because Roger's backing her play (in a way). Even if her business fails (although it appears to be doing quite well), she knows her son is going to be fine. It's that freedom that lets her make the bold move of starting her production company.
Roger
Roger remains the perpetually charming silver fox. He'll drink and smoke and eat us all into the grave, and crack wit while he does it. And we'll be jealous of him for being able to indulge as a bon vivant, and love him anyway because he'll make us laugh. That part doesn't change. What does change, however, is that Roger has, apparently, found his real match in his third wife. She can go toe to toe with him and doesn't take his crap. In a way, it's a return to what he might've had with his first wife, but age has, apparently, freed him of the desire to chase skirts anymore and be able to really enjoy a woman who can match him line for line, and drink for drink. And hey, he even learns French for her.
Peggy
In some ways, Peggy remains herself. She's prim, uptight, and risk-averse. There's a brief moment where she seriously considers Joan's proposal, but turns it down, and hates herself for doing so (hence her lashing out at Stan and the whole "Spoken like a failure!" line -- that's really directed at herself). But she finally does take a risk -- just not a professional one. She puts her feelings on the line with Stan, lets her defenses down, and is actually able to enjoy the part of life that isn't work. In a way, you get the sense that this makes work that much more bearable for her. If Peggy's entrance to McCann was a testament to "She'll be just fine" in a professional sense, her relationship with Stan leaves the viewer feeling the same way about her personal life. But bear in mind, it's not as if she suddenly became a different person. She still turned Joan down, and from the look of it, that was a risk that would've paid off. So, it's not quite as "happy ending" as it could've been for her.
Don
To me, Don's arc this season is the most interesting. First, it perfectly mirrors the opening credits. He does go through this long fall as he sheds his life and ends up at the yoga retreat....only to wind up right back in the chair, smoking a cigarette. That ending is strongly implied in this episode, both in Peggy's "Don't you want to work on Coca Cola?" and "McCann would take you back in a heartbeat" lines, and in the Coke ad. So, in terms of "But what happens to Don?" the short answer appears to be "He clears his head, goes back home, and invents the Coke commercial."
But to me, the real purpose of this last half of the season is Don's emotional journey. He sheds all aspects of his former persona as he travels west. He confesses his sins to various people, takes "penance" (in the form of a phone book to the face, the loss of his car, rejection by Stephanie and his kids, etc.). To my way of thinking, Don's emotional journey has ultimately been one about coming to terms with himself and learning about love. I know that sounds hokey, but if you look at Don's background and the events of this last episode, I think it's pretty clear. Don spent his childhood hated by his father, living and working in a brothel where "love" was bought and sold, he went to war and took another man's identity to come home, and then spent the rest of his life running from his past. All of that, ultimately, translates into Don really...not loving himself and not believing himself worthy of love. It's why all of his romantic relationships are based on power, and especially him having it. When the relationships start to spin out of his control, that's the point where he moves on, starts over with a new woman, and thinks this time it will be different. Except, it isn't. And he's always drawn to finding another woman that he can "make" love him because, again, he has no idea what love is.
The penultimate scene for Don, where the other man confesses to feeling invisible and not even knowing what love is, and Don's embrace of him and recognition of his own demons in this man, that's an incredibly powerful scene. To me, that, plus the very closing scene, is all about one fact: Don Draper/Dick Whitman has finally made peace with himself and allowed himself to just be who he really is. For years, he felt that the "Don Draper" thing was a persona he adopted. What he failed to realize is that the persona is still him. He created it, sure, but he created it. He is literally a self-made man. At the very end, I get the sense that he's realizing this or something like it, and has finally forgiven himself and learned to ultimately love himself. Even if that means loving the fact that he uses "love" to sell nylons for a living. He can still be worthy of love in spite of what he does. And ultimately, I think he comes home to McCann, at peace with himself, and is able to knock it out of the park with the Coke ad.
So, again, Don changes in some really critical ways....but he's still Don at the end. He's just a happier, more settled, more secure Don. To my way of thinking, that's about as happy an ending as anyone could ever ask for.