At the film's start we're introduced to a couple in their (I'm guessing) later twenties who've been married a few years. They're downright adorable right down to their crossword puzzle races in bed. Having been together a bit they've noticed that hanging out has begun to trump sex. After a night hanging out with their friends their pillow talk turns to the idea of each of them being with another person for one night (aka the "freebie" of the title). From this point on the film's arc is fairly predictable - at least to anyone who has seen a movie on the problem of separating rationale planning (this sounds like a good idea and we can handle it) to the emotional response (which just is). It also seems equally predictable to everyone in the film short of the couple involved. Interestingly enough seeing that this could not quite work out as planned seems to be an issue that crosses national and age boundaries. In Palm Springs I saw a film with very similar themes - A Rational Solution - with roughly similar results. Though it wasn't nearly as enjoyable as a film.
Even though the arc may be predictable the story is edited together in a way that held my interest though I strongly suspected the final destination. And as mentioned before the main couple had me sold from minute one - without their natural interactions I doubt I would have liked it that much. My understanding is that the script was largely improvised - so hat's off to all involved for the natural dialog. Technically the film is well put together visually and audibly. Managing to preserve the natural feel of mumblecore flicks without the negatives (such as an inexpensive look and poor audio). If you've liked recent films by Lynn Shelton or involving the Duplass brothers, etc. I'm pretty sure you won't be disappointed. And even if you don't particularly care for the genre as a whole this one may start to shift your thinking.