For me personally, all dislike of the raid revolves around Nihilus parts. The mechanics are slightly annoying but that isnt it. Its the fact that I have to fight him 4 times for for a total of 20 squads. My 60M guild has 1 JTR and we do t4. So I have to spend 5 teams twice in phase 1 and 5 teams twice in phase 4 - JUST on Nihilus parts. So that tedium coupled with the fact that his mechanic is annoying just sours the whole raid. They just need to reduce his HP in the lower tier raids so us lessers dont have to fight him 4 times. Fix that and the raid is much better off the bat.