Really bugs are the biggest problem with Soa - balls 1 shotting you, balls chasing you on the platforms after phase 2 is over, missing platforms, bugged pillars and so on. If it doesn't bug we usually 1 shot him without any problems.
Oh and the most annoying bug of all is the battle res bug, more then half the times it doesn't work even if the debuff is not up. This is a general bug though, but it's more obvious with Soa since it's the longest fight, and if you use battle res in phase 2, by the time you reach phase 3 the debuff will be gone but you can't use it again.