I like every boss until i met Zhaitan. Yea i understand that we have been killing off his power source and weakend him, but like, they tell to us that these dragons are forces of nature, massive and very powerful. Yet all he does is just destroy some parts of the ship, flies around, lets him get shot...twice and then crashes into a random tower which just so happend to be there. He then spends most of his time just staring at you, not bothering to spawn any adds, not letting out any howls or anything, waiting for his death.
Wish they made us kill each of his body parts or something, each part having a different mechanic and a jumping puzzle.