I watched the finale again and loved it even more the second time.
At first I thought Cassian's jump to the rebel cause and statement to Luthen to "kill him or take me in" was a little sudden/extreme, but re-watching the episode it was great to see his interactions with his friends on Ferrix, his visual responses to Maarva's speech, etc. This all made a lot more sense on the second view. I think originally Cassian was going to leave with Bix and his friends, but realized he couldn't keep running and hiding, and that he wanted to move to a more active participation mode in the Rebellion.
This was a fantastic, adult oriented Star Wars series. I still like The Mandalorian and the more kid oriented content, but its great they can do something more serious and adult in the same universe.