MOP: 522 4 Pc set Shadow and Holy Priest working properly? PVE

Hello guys, how is the 522ilvl 4 pc set bonus on shadow priest? Does is give a lot on the DPS? Does it make Shadow Apparition top 3 damage from recount? Does it give more Shadow Apparition?

For holy spec. does 522ilvl 4 pc working properly? Well it was so OP before it was fixed, you can eventually solo heal 10man TOT with it but after it was fixed it went down a lot. Can anyone enlighten me? :) Coz I am planning to buy the 4th piece with my remaining coins and I want to make it count. I hope someone can give detailed information :)