I killed Kil'Jaeden Mythic a couple of weeks ago and I think this raid is a total pile of garbage. The bosses are toxic, unoriginal, unforgiving and there are far too many soaking mechanics which led to class stacking and immunities being completely overpowered. Even after many nerfs having several rogues and mages still is a massive advantage. At first it was a requirement (5 rogues KJ first kill say hi).
Pre nerf mistress, Avatar and Kil'Jaeden were neither good, nor fun encounters to progress and by far the biggest offenders. As for the other bosses, well soak here soak there and they roll over, the only ones a little fun are Sisters and Maiden. Unless you got jihadi melee, that is.
Neither from an encounter nor class balance pov was this a pleasurable raid to clear and I'm glad I only have to farm that shithole a bit more, before Antorus releases. It's obvious this place was rushed and just like the rest of 7.2 it was released to push out some content, while the real effort and resources went to Argus and hopefully Antorus.