Oh come on, that mess of a story line that they made as they went along? Starbuck coming back to "life" and then just disappearing again, the bs nonsensical ending, and then deciding 3/4 of the way through that there are cylons on board and they have been there the whole time? It turned into an absolute mess. Also, "All Along the Watchtower", really?
It started off great but the writers never had a plan and ran out of good ideas and started tripping over their own feet. They wrote themselves into a corner numerous times but couldn't figure out how to get out of it. They also managed to make Starbuck the most annoying person on any planet.