It successfully sideswipes with a concept that becomes necessary after the stagey naturalism of the dinner party, extreme zooms and shakey cam that at least feel earned by an improv vibe. At ends with the 'hard' sci-fi of the mechanics, which is more interested in trickery than resolving its emotional conflicts of diverging choices. Clever but I didn't need to revisit after it had revealed its tricks.
Made with only 50K, Coherence is a remarkable achievement and incredibly watchable. It may be rough around the edges, but it's a really fun mind-fuck of a movie that will keep you intrigued and guessing until the very end. Giving the small scope of the budget, the ideas this movie has are massive. While its ambition deserves 5 stars, the craft is at a 2 (can't really blame them for that) and the ending is a mess.