If I felt like it, I'm sure that I could come up with a number of things that bothered me about this book, but I don't feel like that. Instead, I'll leave it at this... 
 Once you get past Emerson's Bella-Swan-esque adoration of Michael, there's a pretty fun time travel story tucked underneath. Hourglass was a complete story, but there's still room for a sequel, which I like. It was charming, fairly innocuous, and it also referenced both Doctor Who and Hermione's time-turner. That works for me.