Oh I LOVE MUBI. I wouldn't be without it, it makes it so easy to effortlessly discover great films that you'd literally never have heard of without a lot of time and a truly expert knowledge of world cinema. The curation is generally great, and out-of-10 ratings system makes it really easty to make a judgement if you're gonna commit or not to a film if on the fence.
I find it's particularly great for Japanese and Korean films that don't get the marketing push the one or two big titles from those markets get each year, also great for archive 60s/70s stuff and increasingly films from Eastern Europe. They seem to be the place now for recently released arthouse-side of cinema releases - Aftersun, Corsage, Decision To Leave are all showing currently, and I imagine Tár, Triangle Of Sadness and Women Talking will likely find their way to MUBI also.
They've also made the interface much better in the past couple of years, giving access to the full catalogue rather than just the 30 films of the month (which is how it used to be, and felt VERY restrictive).
Grumbles:
They sometimes get a bit carried away with their themed seasons - especially if its a genre/subject you have no interest in.
Sometimes theres stuff clearly unavailable cos its on BFI Player instead - the Kurosawa catalogue is an obvious example.
They used to show a lot more Japanese/world animation that isn't Studio Ghibli but that seems to have entirely stopped now.
They can be a bit snobby about seasonal films - they seemed reluctant to show arty/classic Christmas films in December, for example.
But yeah, MUBI and Hayu perfect combo
