Pretty much agree with @randompadley except that the last 20-30 minutes weren't much more exciting either.
The movie seems to have been written around one core idea but failed to even setup a believable "celebratory weekend get-away" to make up the runtime. Add in tons of classic facepalm horror moments and shitty characters et voilà.
I'd honestly have skipped this seeing who directed it but with the other poster variant it made it appear like there might be something cool going on (with the flipped perspective of the house and the figure in the sky). :thumbsdown:

[spoiler]And while I don't need a resolution to a movie necessarily the reveal that it's just a random stranger doing this only left me with more questions in how this all played out. Kinda hard to believe this setup over a weekend and I doubt the MO should just have been that he likes watching and then killing strangers. I mean he rents the place beforehand to set it all up so just how many places could he possible have "sliced up" by this method... His plan was also far from foolproof. They could have easily have made it away (as shown by the stupid chase scene in the forest)... there is also evidence on their phones, etc. so why even bother removing all the cameras :rolling_eyes:.[/spoiler]