I thought that Julie Cross was really quite successful in her portrayal of time travel. I have read a few books that involved time travel and most of the time the semantics and science of it really gets in the way of the story. I thought the explanation of Jackson's abilities was clever and fresh. 
 I really enjoyed the main character Jackson. I thought it was nice to have a male lead which seems rather unusual these days in young adult novels. It was also refreshing that Jackson wasn't super duper love sick and emo over his girlfriend. His relationship was real and actually a joy to read about. 
 Tempest is the first in a trilogy, but I would say that this could be ok as a standalone novel. As much as I did enjoy it, I'm not chomping at the bit going crazy to read the next one because there was an annoying cliffhanger. I can leisurely await the next in the series and see what Jackson finds out about his past and future.