FULL SEASON SPOILERS HERE!
To me, I was kinda disappointed when I was watching the behind the scenes special, and they are talking about their writing process. Here is yet another show that writes by the seat of their pants and doesn't plan anything out. They wrote in the final four like THAT episode. It's not like they knew about this from day one. That sort of story writing tends to have continuity problems.
For example, their "wild card" cylon, the Indian chick, ended up being a character with no depth and a confusing personality. She was a minor character, yet she was one of the five. They didn't delve into her past at all. In the end, they didn't know what to do with her, so they just killed her off. A sorry excuse for plot direction, and this is a why you plan this shit out ahead of time.
Another thing, what the hell happened to Galen's kid? Here's one of the fabled "important" half-Cylon/Human hybrids, and you don't even see him after his wife is killed. Galen gets so depressed about the distrust that he experienced that he goes to Greenland all alone, without even his own kid. Again, lack of planning, coming from making shit up on the fly.
The angels? Oh, they were just angels. No explanation. Another cop out. Another plot element gone to waste. Oh, and Starbuck was an angel, but we just kinda wrote that in at the last minute.
JMS planned the story out with Babylon 5. He knew what the fuck was going on everywhere from the first episode. Sure, the guy wasn't the best dialogue writer, but the overall story arc made it a kickass series.
Overall, I guess I was pleased with the ending. In a way, I thought it wrapped up everything too cleanly. Or to put it in a different way, there was no build up for a lot of things. It was like they wasted all of that fourth season to put in every surprise in the final two hours. It reminded me of Farscapes rushed ending, but that was because the assholes at Sci-Fi (or Fox or whoever) didn't bother renewing the last season. (God, that would have been even more fantastic if the whole last episode with the black hole was actually fleshed out into a season.) BSG didn't have an excuse.
Rosalina: But you didn't.
Robert: But I DON'T.
Rosalina: You sure that's right?
Robert: I was going to HAVE told you they'd come?
Rosalina: No.
Robert: The subjunctive?
Rosalina: That's not the subjunctive.
Robert: I don't think the syntax has been invented yet.
Rosalina: It would have had to have had been.
Robert: Had to have...had...been? That can't be right.