A Cure for Wellness is most certainly not going to be for everyone. It's spectacularly, deliberately, uncomfortably ugly (albeit, in a bizarrely beautiful way). It's story is flawed, it's long (two and a half hours all told), it's slow, some of its setups don't evolve into payoffs, it's not half as mysterious or clever as it might think it is, and it can't even hold to its own mythology 100%. But I loved it.
Final rating:★★★½ - I really liked it. Would strongly recommend you give it your time.