As a person who wholeheartedly finds all fictional depictions of time travel icky, I still mostly enjoyed this.
The "science" is sketchily quoted-from-quotes, the dialogue is repetitive and two-dimensional (haha, see what I did there), and the characters are gloriously stereotypical.
On the other hand, the premise is interesting, the action moves along well, and as a debut novel it is pretty well done, and I'm keen to try the sequel just to see if it gets better.