I hated the ending (spoilers on ending follow this line!).
I hated it because it seemed like one of those ending written almost out of spite, as a fuck you to the viewer and characters. Not only is it sad with no redemption, in a show that has given to indication at all that it's gearing up to be a tragedy, but the whole season seemed designed to personally make each character's story as tragic as possible. They carefully avoid making their lives so bad that the sacrifice still seems bad, but give them the most depressing arcs I've ever seen in a TV show that was supposed to be lighthearted.
In case anyone is interested, here is the evidence....
Diego: Throughout the series he has been chronically undervalued and underappreciated by his family, until he meets Lila. We are supposed to believe that because he complains about a job that doesn't give him time to piss, and a family where his beloved wife sneaks around and gaslights him, he deserves to be cheated on and die thinking his wife doesn't love him. Worse, Lila's main source of unhappiness is her alleged hatred of domestic life - yet her life with Five is domestic as it gets, dreamily watering strawberries in flowery dresses. Diego has always envied Five's job and life, making the betrayal even worse. The show screws him by leaning into his worst fears: that he's inferior to his siblings and undeserving of Lila's love.
Luther: his big theme is isoaltion. He was stuck on the moon and has always just wanted to forge genuine positive conections with his family. The only person who has ever loved him dies and his family acts like it never happened. On his deathbed he asks them to share some positive moments and they all mock him and refuse.
Five: lives a whole life alone in an apocalypse. Gets back and doesn't stop trying to save the world and his family until season 4 (he gets no breaks unlike the others, he keeps time jumping straight to action). He then gets 6 years living a normal life, before getting stuck underground for 7 years and falling in love with a woman who is just using him to pass the time. This man craves love so badly that he was romatically invovled with a mannequin, and his whole purpose in life has been to save his family - so the show screws him over with an even more painful and one-sided romantic relationship, that costs him loyalty to his familty as well. They also dumb him down by making him unable to solve simple clues that Luther of all people work out, and openly mock him for it.
Alison: wanted her huband, her daughter, and to prove she could get somewhere without her powers. The show make her husband leave her, for no reason and without explanation, and make it very clear that she is nothing without her powers. Then she dies.
Klaus: we've always wondered what a sober Klaus would look like - someone strong enough to face the underworld with a clear mind. Turns out that he's a shrivelling wreck without the drugs, but that's ok, because he can't stay sober as soon as he gets his powers back, anyway. Klaus literally never masters his powers or overcomes his addiction. He just dies, having done nothing this season but become a sex slave.
Ben: whole family murdered, prison, falls in love, becomes the clense, dies.
Viktor: possibly the most self actualised one. Does repair some of the childhood family trauma, even though his carefully reinvented life comes crashing down when Ben spikes him.
Lila: where to even start? Five murders her family when she was 4 years old. She's trapped by the commission, abused by her adoptive parent, is insane, but finds a good partner in Diego. She then gets trapped in a life she hates, then trapped on an underground for 7 years desperately trying to get back to her children. She gets back to her children after 7 long years, and a few hours later puts them in the same underground and waves goodbye forever. Then she dies.