The camera is not the worst on the ghost doku fight, to be honest, it is not great either, but it is one of the fights where it never got in my way, never had trouble with collision at all. To me he is not enjoyable, but he is not a problem, which is better than half of the bosses of the game already.
Fiend Ryu, i have gripes with it, the fact that i can't find anything consistent about him, when can he be hit, where are his weaknesses, how he can simply cancel into ninpo, and have an unlimited ammount of those, if i could understand properly how he works and when he is actually vulnerable, i think i would enjoy the fight more.