It can cheat death but only if the overkill doesn't outdamage your cheat death heal. And if it kills you over 35% with one swoop it won't kick in either right now on the beta, which is supposedly a bug. We hope.
All in all, it's an extra defensive but let's not pretend it's purgatory, cauterize or the rogue cheat. It also competes with Graceful Spirit (which is always nice on fights that have a section like Imonar bridge) and Wind Rush Totem (which is useful on a lot of fights in Antorus). Doubt I'd take it in raids, definitely would in M+.
Like someone said as well, most healers feel a bit bland right now due to the loss of artifact traits. I've played Holy Paladin, Resto Shaman and Resto Druid, and while all 3 are looking solid again for BfA, they are a bit boring. But i'll take boring performance over a fun shit show