Right from the start, the last episodes were amazing with twists and turns and shockers. Big shockers that knocked my socks off:
Dualla committing suicide

Felix Gaeta leading a mutiny with Tom Zerrick
The revelation of the final Cylon
Whatever the F Starbuck was.
Chief Tyrrel not being the father of his son
Coloniol Ti knocking up Caprica 6
The Final Final being alive on Earth before it was nuked but planning everything
Probably a few more but I can't remember
One of the highlights from season 4.5 was the uprising led by Gaeta. Very high, tense, nail biting moment full action, intrigue, betrayal, and bucketloads of drama. I didn't think Gaeta had it in him, to lead an uprising. In an episode as full of drama as this, the one scene that had me in stitches was when Zerrick ordered the Quarum to be killed. I imagine thats what people feel like doing to their elected representatives from time to time.
Sam Anderson, one of the final five, taking a bullet to the head and becoming an Oracle, I guess for the base ship was another great moment.
And of course the final battle scene between Battlestar Gallactica and the Cylon Colony was a fantabulous battle. A true Civil war. Cylon vs. Cylon, Centurian vs. Centurian and just when it seemed everything could've gone to shit The Final Five offer John -the crusty old man Cylon- Resurrection but its stopped when Tyrrel chokes the shit out of the President's former aide when he learns she killed Callie.
The ending could've been perfect but it had one huge flaw: Gaius fucking Baltar got to walk off with Caprica 6 and live happily ever after. That pissed me off so damn much. From the first episode Baltar was nothing but a selfish prick. He manipulated everything and everyone to serve his goals. Not to mention the fact that he is pretty much responsible for the original genocide. I really can't past this. For all the bullshit prophecies he was a part of, all he did at the very end was pick up a little girl and take her into the adjoining room and he even fucked that up when the Cylon grabbed her and was going to blow her head off.
Dualla: Dead, Gaeta: Executed but Baltar gets live out his remaining days in peace and happiness:

More later