This looks like the most boring movie ever. This concept worked alright, I guess, in The Raft because that was part of one of the Creepshow movies (2, IIRC) and thus only had to carry about a third of the running time. And comparisons to Lifeboat are unwarranted. Hitchcock was from a time when characters were fully fleshed out and made to be interesting people. These characters are typical slasher movie fodder and therefore completely uninteresting.
That said, I also hope they're already working on a sequel. It would be called "Above" and be about an uninteresting group of horny teenagers attacked by drop bears.