Best thing they invented in a long, long time, no question. However, with how bad average player is, I'm sure Blizzard will nerf them into oblivion, making them absolutely trivial. Hell, they will be more or less trivial in a few weeks when we have maxed cloak and talent tree, even on 5 masks.
Also, funny thing about visions, is how they require a different skillset than m+/raiding. I myself know several decent mythic raiders, who absolutely suck at doing visions, despite usually playing some of the best classes for them. But I guess when you don't have entire raid carrying you, and you can only rely on yourself...it shows you who has brain and who doesn't