Hourglass is definitely an interesting book. The first few pages pull you in when our MC Emerson (no offense, but what's with all these strange names? Hudson, Hadley, and now Emerson) is confronted by a lady who appears to be dressed in 19th century attire. Emerson then proceeds to thrust her hand through this woman to open the door, which causes the woman to disappear. Interesting. However, the pace goes downhill from there. Or should I say uphill, because its so. Freaking. Slow. I found myself just reading 5 pages at a time then getting bored so I would go do something else. 
 The first half of the book is just about Emerson "coincidentally" bumping into love interest Michael like literally everyday in the most random places (when jogging, or at a coffeehouse). It seemed forced really. There's no way one could bump into someone that many times in a week. What's worse is that said love interest isn't allowed to have an intimate relationship with Em, because he works for her older brother. So no romance..yet. 
 This book is about time travel, which I found was a creative idea among all the other paranormals that are about vampires and witches. However, you could tell that McEntire was heavily influenced by Twilight when she was writing this book. Not as bad as say, Halo by Alexandra Adornetto, but I definitely had my eyes rolling at some parts. I know that all authors' main goal is to be as successful as Twilight or THG, but its not going to happen if you rip it off of them. THG came out after Twilight, and its not about vampires or werewolves, yet it proved to be a huge hit. THG is not like twilight in any way at all, and it was widely successful. So please authors, come up with your own stuff. Yes, that includes little details like having nightmares in your sleep and then being woken up and comforted by your male relative. :) 
 Sorry for rambling. Okay, now for the plot. Emerson somehow got this ability to see "ripples", which are people from a different era (not exactly ghosts, but similar), around her after her parents died in an accident. When she touches them, they go poof. She has a hard time deciphering who's real and who's not unless their clothing is definitely from another era. Emerson's brother hires an agent from a company called the Hourglass to help her with her ability and a bunch of crazy stuff goes down. 
 Although the beginning was turtle slow, the second half balances it all out because it was AMAZING. I literally could not put the book down. It was exciting and exhilirating. The ending was definitely unexpected for me. Characters who seemed good turned out bad and characters who seemed bad turned out good. 
 There were some people and things that I felt weren't touched on enough and whose stories felt incomplete. For example, Lily, Em's best friend, was only talked about for maybe a total of 15 pages, and then we didn't hear much about her at the end. One thing I loved though, was that McEntire handled her description very maturely. Only by her description and last name would you infer that Lily was Hispanic. I loved how she wasn't described by her race, and how you would have to guess that she was Hispanic. That made me appreciate McEntire in a whole new way. (I am in no way saying that being Hispanic is bad. I just hate how nowadays characters are described by race as if that really factored in who they are as a person. Tis all :)) 
 Sorry for the long ass review. Although I had a lot of problems with this book, the creativity and emotion set in it outweighs all the negative aspects. I can't bring myself to give it 5 stars, but it does deserve at least 4. Great debut, now onto the sequel :).