The movie is based around three characters - Ron & Dale (who are "on the run" from the law) and Andrew (their would-be hostage). Teresa Palmer is the most well known of the cast, and you can see why she is expected to be a fine Australian actor in the years to come.
I would say each of the three main performances are good, to very good. This movie kept me interested and whilst you're not meant to "believe" the events that unfold, it's not totally unrealistic either.
The ending of the movie is also not what you'd expect, which only adds to the reasons for recommending it if you're looking for a good suspense/thriller film.