When looking at the discourse of this film the question generally resolvs down to the nature of the unsimulated sex: is it a gimmick or is it a story-telling device.
Contrary to the others complaining about the live music interludes, my issue is more that they are pretty explicit in describing the theme of the previous or upcoming segment (or both depending on the point). It's an interesting approach, and one that is not unique but is not handled poorly here.
But back to the sex. There is a large amount of story-telling done through the sex scenes, mostly in how the two of them behave to one another when it comes to sex. The eagerness, the experimentation, the masturbation are all used to give you a glimpse through the relationship as it grows and continues.
But is it just a gimick? To be honest, it sort of is. It allows the film to have a naturalistic style and approach where the whole experience feels very real, which does add a level of normalcy to the whole events. Would simulated scenes have impacted this so negatively? Possibly, but Room in Rome managed to craft the same story-telling beats and moments through simulated sex.
The film is relatively average, and not something I would tell people to seek out.
The Troubles were a truly fucked up conflict.
The British education on The Troubles is weak, and people are generally unaware of the events that lead to the escalating violence that defined Belfast's recent history. With this context, the film does a good job of humanising and villianising all sides with a level of fairness that is not often seen in British made media about The Troubles.
Soldiers are shown as both young men (often from a tough situation) with very little in the way of stakes in the fight and as the armed support for a ruthless and dehumanising state. Senior officers range from those who want to minimise the use of riot gear (because they're not their to start a riot) to those who are happy to kill their own to escalate the situation. Catholics range from the innocent, the angry, the rage-filled, the tired, and the violent. And it has a shown a decent understanding of what was happening with the IRA at this time in history, and how someone can end up involved in the IRA due to the circumstances of their lives.
All of this is weaved around what is effectively a cat and mouse chase across Belfast after dark when being in the wrong part of town is a death sentence for a British soldier.
A Cure for Wellness commits a common sin of 'horror' films post the reguvination of the genre: it isn't actually a horror film. That is not a criticism of the quality of what the film is, but going in with expectations of a horror film is immediately going to leave many uncomfortable with what they see as it doesn't fulfil that niche.
What it is instead is a slowly building psychological thriller where the protoganist slowly begins to lose his grip on what is going on, which builds to a confrontation at the end. Unfortunately the film seems to think towards the end that we buy into the explanation offered in universe to dimiss their concerns. I am not sure if it is just a tonal mismatch as their story is so obviously a lie while filmed as if it could be real, but it sort of falls flat.
However, the actual story, hidden behind two and a half hours of wandering through a sanitarium, is a really interesting concept. It's genuinely neat, and that aspect of the film is worthy of a film. It is just a shame that the film it got was not able to do true justice to the idea. A well crafted film, which shows a lot of skill in lots of places, but really could've done with a significant script overhaul and edit for time, that doesn't quite reach the heights that are tantalising close.