Absolutely frakking amazing. Ron Moore did not disappoint (nice cameo, btw). As the episode unfolded, I found myself going "Oh, I get that now! And that! It all makes sense!" The battle was epic, and the ending was very satisfying. I think they went a little over the top at the very end, with Hendrix's "All Along the Watchtower" and the montage of robots. But I like that they tied the series back to the overall message, that all of this has happened before, and all of this will happen again. I guess the question is, will we as humanity break the cycle this time?
One final salute to the Battlestar Galactica, finest ship in the fleet.
Edit: Also, I concur that Kara was an angel ever since she dove into the maelstrom. It was her destiny to die, so that she could return as an angel and lead the fleet to its end. With her task complete, she left.
Another edit: Btw, looking forward to playing the Battle of the Black Hole in Diaspora.