I've mained shadow through good times and bad since B.C. This expansion finally broke me of that. Pretty much from top-to-bottom I've disliked what they've done with the spec. I wasn't a fan of the class fantasy--my priest is a lot of things but she's not insane nor have I ever thought of her that way--and I've not cared for the class mechanics at all during legion, especially STM. When the meta around a class centers on a single spell you don't much like that's tough to get past.
I thought the choice to go either single target versus dot damage was interesting and I'm sorry to see it watered down. I know I'm in a minority there but I've been managing dots for years now and have gotten a bit weary of it. So I'm playing a frost mage at the moment and watching the patch notes.