The finale is a solid 10/10 until the last 45 minutes,
Yep, could not agree more. Hell, after the first hour I had felt that I got my two hours worth. I looked at the wife and said -
"Damn, we still have another hour to go"
It was that filling and productive ... and good.
...
then things get murkey.
Understatement.
As you brought up, the show always had a certain underlying (or in the forefront) theme, which is the aspects of humanity: Love, Survival and Philosophical Reasoning / Religion. The belief of the Monotheistic vs. Polytheistic ideologies was often entrenched in the show and really made more powerful with the “fight for survival of the species” aspect. However, the show never seemed to be about Supernatural elements.
Now some may argue that point or judgment, but that is how I always understood the show. The “ghosts” were not ghost’s as much as angelic bits of subconscious. Holy guides if you will. And yes, I can understand if you ask what the difference is. Hard to explain, but those that have watched the show should know what I am trying to say.

The show, as religious as it was, was never supernatural, or more to my point of aggravation and ire, this show was never paranormal.
Until now.
What a crock.
I can almost … almost deal with not being shown what Thrace actually was or what we suspected her to be, and fine … some writers like to “let the readers/viewers make up their own versions of what happened” , but ending her story like this was nothing short of a non-lubed anal intrusion.
If they would have had her walk out of scene, slowly disappearing into the horizon (or some other visible means of exit) I would still be pissed at the open-endedness of it all … yes pissed, but at least then I would not be feeling like I just watched the last episode of the X-Files. Now, I am pissed doubly so. Vanished? Poof? Ghost?
And a ghost that interacted with everyone and everything? A ghost that could fly a ship? a ghost that could land that older Viper and have everyone touch said Viper, proving it has density and therefor a real F'n ship?
BULLSH!T
And then the last 5 minutes … sweet lord why? Why have the "Not Baltar" and the "not 6" there talking? Why have them talking ... explaining that crap to us? They leave us "guessing" (with a sore ass) on the important stuff, but now they want to drone on about this?
Here is my ending …
Go over the hill, see the city, see the text -150,000 years later (just like the show) and then show the walking robot on the television … the end.
There. You have “us” evolving to repeat the same Cylon process over again. You show the viewers what will transpire, without actually showing them.
AARRRHHHH
and, damn it ... Starbuck … just … what the hell?
Boooooooo.
Booo-Hisssss
Poor ending …
Stop watching this show as soon as they land on the planet … just stop it and walk away and you will be much happier than I am today.