Well that was actually Dean Stockwell's idea - originally Tigh would throw him off the balcony, but Dean phoned the writer up and said something along the lines of 'Cavil knows the jig is up'.
About the finale as a whole -
I loved it up until the last five minutes. The action was great [Cylon on Cylon, if only the old ones did some trash-talkin'], I liked Racetrack returning [then becoming the most destructive single character in the show], most of the flashbacks seemed to make sense to me [Adama's could have definitely been compressed, though, and Laura only seemed to get one because she had second billing], and Laura dying was really sad. While I didn't expect a happy ending, I liked it.
Then we jump into the future for a cheap cameo and a montage of goofy robots. I doubt that's how the Cylons came to be.