I think you have watch this in the right frame of mind. This is arthouse cinema set amongst art, in a house. Well, glamourous, high-rise New York apartment, but there you go.
When art-thief Willem Dafoe lets himself into an apartment in New York with the intention of nicking all of the priceless paintings, things go awry, and he finds himself locked in the apartment with no apparent means of escape. So begins an overlong fly on the wall experience of what happens to this man, slowly unravelling as his will is whittled down every day. Castaway in a building, really.
During his incarceration he begins to purposefully create his own art. I mean, you would, right, if you're of a creative bent with nothing to do and nowhere to go? Even inadvertently, he is continually creating, if you judge the lengths he goes to whilst trying to escape, as an example.
"Cats die, music fades, but art is for keeps."
Whilst painfully slow at times, this I imagine is not without purpose. I would have happily seen this shortened by fifteen minutes, maybe more even, as I do not see where the extra time would have been required to get across the story or make this character arc more pronounced. Forty percent of this was improvised by Dafoe, according to the director, and whilst I have no problem watching Dafoe in anything, I'm not sure we needed quite that much of him here. Whilst this performance is not narcissism, it does hint a little at potential self-indulgence.
Skilfully and artfully directed, this is worth a viewing, but don't expect to find yourself either gunning for or berating the lead here, as your own moral standpoint may get in the way. But like they say, art is in the eye of the beholder, and just like this, you bring yourself and your unique opinion to it.