Todd has his own place, a girlfriend that understands him, and reconnects with his mom. Peanutbutter takes the time to find himself and not attach all of himself to other people and trying to please others, and gets to be a figure in a TV show he loves and makes changes while staying Bojack's friend. Princess Carolyn finds a match for her, and has a manage of her personal and work life finally, being in the position she's wanted to be and worked hard for. Diane finds stability and happiness, and leaves behind her past life as she's ready to move on from it all after this last night to say goodbyes.
Hollyhock is really sad to see, but I also understand it. I expect many to be upset about it, but I think it's appropriate. Bojack's past sins she wasn't comfortable with and that actively showed at the start of the season, and so Bojack lost the possibility to connect with his sister again. She had to cut it like this because she both couldn't face him, but also knew if she did it in person or heard his voice she'd let him back into his life. But Hollyhock can never be comfortable with the things Bojack did in the past, even if he's different now and she knows that, so they're no longer in each other's lives and she ends it with a letter to cut ties.
And finally Bojack, he gets sent to prison, but actually it's strangely the stability he needs. The past came and made him lose himself one more time, he is stubborn and needed all of his past to come back up and come to the surface. He's still Bojack, but he's more self-aware than ever and does take responsibility for what he's done. There's things he can't go back and fix, there's irreparable damage he's done, and some things he'll never get back. But there's some things that stay the same, and there's still things for him to live and do, and he's now a better version of himself. He's still Bojack and very flawed, but a better Bojack than he once was.
The last two episodes were the stand-outs, I think this might've been my favorite "surreal episode" the series did. I got what was going on immediately, but even then it was wonderfully executed, and I even enjoyed a lot of subtle details, like the dinner they're all eating being their "last meals" they had before they died, and the symbolism in their stage plays of how they all died showing the best and worst parts of their life they talked about earlier resurfacing in weird mixed imagery of their best and worst combining (and in his dad's case, how his best AND worst moments were the same thing, IE him jumping off the bridge to die, and when trying to make peace with himself he can't, because he didn't live a life worth living and he realizes it right then he wasted his life by being who he was and not caring about the important things as death comes and takes him). The visuals were wonderful, and I think it might be one of my favorite episodes of the series.
The last episode is very melancholic, but it works because the writing they ended with each character was absolutely stellar. The last talks with Todd, Princess Carolyn and Diane were all written excellently, and the actors nailed it. This one lives purely off its writing for me, which is excellent so it really works.