I'm not sure exactly what this is.
It's like someone has watched a couple of Beckett and Pinter plays then a Carry On film and decided to have a go themselves.
It's full of inexplicable silences and overblown slow prop mishandling. There's an over- current of drabness with a lot of very affected acting. There's the conversations that go nowhere and have no purpose.
All of these things can be great, if done well... and a lot of it has been done well but still isn't great. There's a mystery here somewhere as to why this has gone wrong; it's hard to point a finger at. Can't fault the actual performances and it's an interesting enough story...It just somehow doesn't work.
If I had to make a stab at it I'd say that there is something in the execution that puts a distance between me and the film. It's the putting together that's made the problem maybe.
I'm coming to the conclusion that they meant to do a play and accidentally ended up making a film. I could see it working as a play, but it just doesn't as a film.