I had my issues, but I ultimately liked the ending
I'm kind of late to this discussion, but I've needed some time to collect my thoughts and take stock of what I liked/disliked about the finale. TLDR, this was a very imperfect closure, but I liked the ending.
My initial reaction was fairly negative. The story felt rushed and underdeveloped, and the characters were not as interesting and complex as in the previous seasons. It felt like all my worst expectations for the finale were coming true. However, the day after I watched the finale, I found myselt looking at it in a more positive light. Ultimately, I liked the ending and the bare bones of the story, and I really wish we could have seen it unfold in a full season.
My unpopular opinion is that the ending, while it could have been happier, is an understandable conclusion to the plot we saw unfold during S1 and S2. Just to mention some examples: at the end of S1, Crowley brought up that the next war might be between angels + demons against humanity. Additionally, both angels and demons are actively hoping for and, in some cases, working towards starting a war that would wipe out humanity. There are countless examples of these entities - even C & A - using humans as chess pieces. So far, humanity has been saved, but never without the help of supernatural influence (Adam, C & A).
And then S2 ended with Aziraphale going to heaven to change things... I'm pretty sure we all knew this wouldn't work, and it didn't. I assume that we would have seen his attempts to change the world in more detail if we had gotten six episodes.
Now onto the ending. I disagree with the interpretation that C & A destroyed humanity. They did their best to save it, but given that most other entities don't give a damn about humans, C & A were bound to fail at some point. I think their reasons for starting a new universe could have been explained in more detail, but I ultimately understand their decision. They wanted better for humans than their current world. They wanted humans to have free will. (On a side note, I think the Jesus storyline ties in with the lack of free will. Not even Jesus can exercise his free will completely, so what hope do humans have?)
I don't see the ending as a commentary on our world - my understanding is that our current world is supposed to be the one they asked God to create. I also disagree with the interpretation that Asa and Anthony are two random men wearing their faces. I 100% see them as reincarnations of C & A, and I do believe they would find each other in every life.
Honestly not sure if anyone even read this far, but thank you if you did! Apologies for the essay, haha, but I needed to get some of my thoughts off my chest.