When I first saw the blurb for this book, I was interested, but I wasn't super excited for it. It's not that it didn't sound great - it did - but I was a little wary of it because I'm almost always on the fence when it comes to novels that center on time travel. At first, I couldn't really put my finger on why I avoided them, but at this point I realize it's because they can be confusing. Getting all the different time lines mixed up with what happened, what may have happened, or actually didn't happen at all can lead to lots of frustration if everything's not explained properly. However, once in a while I find something that handles this subject believably and is told in a way I can easily follow. I was hoping I would find a winner with All Our Yesterdays, and thankfully, I did. It easily exceeded my expectations, and I would even call it one of my favorites of this year so far. Honestly, though, I should have expected better - almost all of the reviews I read beforehand were positive. 
 Another aspect of time travel that can by tricky is the science. I don't know much about the subject myself, so it's not like I can point out anything that was definitely unrealistic but from what I could tell it seemed to come together well. I liked how the book didn't really linger on the science lingo about how the time machine worked, because it really wasn't important to the story and I probably would have skimmed that part anyway. When the story first opens, Em is sitting in a cell and she and her friend Finn are being tortured on a regular basis because their captors want to know the location of some mysterious documents. Em finds a piece of paper in a sewer drain that instructs her to kill "him". Sounds like an interesting beginning, right? Well, I was almost immediately hooked. The only thing that kept me from loving it at first was the fact that I wasn't completely sure about what was going on. Despite what I said earlier, All Our Yesterdays is a bit confusing at first. But I promise that if you have some patience and continue deeper into the story, the pieces will come together eventually. 
 The narration of the book switches back and forth from Em to Marina. Marina was much harder to like than Em, but really that's not her fault. She's a fairly naive, slightly superficial girl who is obsessed with her childhood friend James and wants nothing more than to get him to notice her as more than a friend. If you took away all the time Marina was thinking of James, you may have a page or two of internal monologue. I know that sounds like it could get annoying, and maybe it did at some point, but it's actually very important to later events in the story. Em is tougher and focused on survival and saving the world, which she is attempting to do by making sure the time machine is never built. There were plenty of questions I had over the course of the entire book, and they were answered one at a time, so I always had a reason to keep turning the pages. Finn was an excellent addition to the story - of the three, he was the most lighthearted and I really enjoyed his personality. I even grew to care about James, and by the end I still did. I'm not sure how much the author intended for us to like him, but despite everything I wanted everything to work out for him. The villain of the story, the "doctor" is named after a while, but for a long time I suspected he would be a flat character who isn't around enough to have much substance. When the secret about him was revealed, I realized how wrong I was. 
 Terrill's writing was pretty good, too - and the funny thing is, I didn't even realize how great it was until I got to the last few chapters. I mean, it was a pretty great story up until then - but it was good in a "I just read a good book, now I'm moving onto something else" way. Not until I was crying towards the end did I understand how much I cared about these people and that All Our Yesterdays had graduated to "I'm going to have a bookish hangover after this" territory. It's been a while since the greatness of something gradually creeped up on me, and I appreciated it. Though I wish the story could have ended a little differently, I appreciated the bittersweet touch. It was uncommon for a YA book and since a lot of them have been startlingly similar lately, the originality was a breath of fresh air. I just found out that there's going to be a sequel, though . . . so does that mean the ending will be happier overall? I'm not sure how I feel about that, but I'm more than willing to read another story set in this world. I encourage you not to overlook this amazing debut, because that would truly be a mistake. There was one thing in particular that confused me about the end. 
 (view spoiler)[I don't understand how Finn was alive at the end of the book. The younger version of both him and James were killed, so it doesn't make much sense that James would stay dead and Finn would not. (hide spoiler)] 
 4.5 stars