This book has a lot going for it. I loved the time travel, the nordic mythology (the tree at Yggdrasil and the three Norns/Fates? So cool), the fantasy, and the magic. This book has an all-around solid plot. It was tight and original - interesting and refreshing (there's beginning to be far too much dystopian and paranormal YA lit these days). Other things I loved are the fact that Tessa lives in a used book store and the secret behind her name (which I won't reveal because it's far too much fun - especially if you're a fan of classic children's lit). A lot of plusses for this book.
There's only one thing holding me back from giving this book a stellar review, and that's the romance. It wasn't awful, just a bit bi-polar. By that I mean that one minute Tessa and Will hated each other (screaming and fighting), and a page or two later they were madly in love. And it seemed to happen over and over again. There was a lot of back and forth and I just wasn't buying it. I would have liked this book so much better if the romance had been better portrayed. Still.... with the cool plot and other good things I didn't finish this book feeling dissatisfied. I really enjoyed it - but I don't think it's earned a place on my bookshelf.