The leads were amazing, but actors can only do so much with sub par writing. While it was good at playing with expectations and dabbled in a diverse range of themes and genres (revenge, abuse, romance, psychological thriller, gore), it did not do any of these topics justice.
The leads had really good chemistry, but they were not fleshed out in the writing. Good suspense comes naturally when there is a connection to the characters, and that's just not possible when they are so two dimensional. If you're looking for quality, look elsewhere. If you're trying to kill an hour or so and are curious and want some twists, go for it.