I might be in the minority here, but I can't stand boss fights of any kind. I play these games for the continuous progression of an interesting story and non-stop fun and action. Rediculous boss fights where you just wait for a pattern and shoot during an opening in that pattern are just annoying and frustrating, and they bog the storytelling down. So I was fine with the final boss fight.
And what I really can't stand are GIANT boss fights where the enemy is 50 times bigger than you. I mean seriously - the Leviathan? Totally ruined the series for me. Just my personal opinion.