Okay, it was decent. Not great, but better than a lot of finales I've seen in my time. Certainly better than the Seinfeld finale, but not as good as the Newhart finale...
However, two points:
1) given that this was a series finale, advertising for two follow-on stories (not even really spinoffs, but more like sequels...), it's hardly a finale.
2) "All will be explained" - hardly. Okay, so Starbuck's not a Cylon (I never thought she was), what is she??? An angel? Maybe. But there was hardly enough explication, except for the "my job is done" BS line at the end. And if she was an angel, why wasn't she hanging out with Baltar and Caprica at the end? And what exactly was her body doing on Earth (1)? How did she get there? Was she always a reincarnation of the Starbuck corpse on Earth (1), and the Starbuck we knew grew up with the knowledge of how to get to Earth (1)? If so, then how did she know the way to Earth (2)? And if that were true, then who was the original Starbuck from Earth (1) (in a Viper, no less...)? If the Starbuck of Season 4 was the returned soul of Starbuck (season 3) after somehow getting to Earth (1) and crashing there, how did she know the way to Earth (2), since all the prophecy crap about her was her ability to get to Earth (1)?
And really, all the fuss about Hera, and in the end she's just Mitochondrial Eve? Cute tie-in, but obviously, since the humans can breed with the Cro-Magnon/Neanderthals wandering around, the importance of Hera is kind of insignificant.
Honestly, I think it would have ended better if they had landed on The Island and Roslin's cancer was miraculously healed... at the cost of one of her toes.