I understand it's ironic for me to be writing a review that says avoid reviews, but there aren't any spoilers in this one. Just try to go in blind and you'll have a better experience. Companion was a great ride. I have a soft spot for dark, R-rated comedies, so keep that in mind. This is definitely a dark comedy, with plenty of unexpected violence.
Sophie Thatcher does a fantastic job, in fact I respected all the actors in this one. They made the most of their characters and it was hard to love, hate, or even figure out who to root for until the movie neared its conclusion. That unpredictability made it a fun ride.
I highly recommend checking this one out if you enjoy violent, dark comedies. For me, it was much more enjoyable going in without reading reviews or knowing anything beyond the fact that it's a dark comedy. I hope you have the same experience.