See more of my reviews on Birth of a New Witch! My copy was an ARC I received from the publisher for review via NetGalley.Though YA sci-fi with lots of time travel and complex science is something I tend to stay away from, All Our Yesterdays was impossible to pass on thanks to all the hype from the publisher and bloggers alike--bloggers who don't often give glowing reviews like the ones they gave to this book. Besides, everyone's gotta get out of their comfort zone sometimes, right? The book is sure to be a hit with sci-fi fans and anyone who understand the complexity of time travel as it's presented in this novel, but people like me with no clue about anything more complex than high school science classes may find themselves lost.It's not often I have the time or desire to read a book from start to finish in a single day, especially if it's over 300 pages. Clocking in at 368 pages, All Our Yesterdays starts out strong and doesn't let up on the action, drama, and excitement until the very last page. It doesn't feel nearly as long as it is thanks to that lightning-fast pacing and our narrators' engaging, unique voices.Though Marina and Em narrate their story to us, the tale they tell around three people (technically six if you count their present and future selves): Marina, Finn, and James. Each one has their own strong personal conflicts going on both now and in the future, though Em's and both James' have the strongest ones of all. Wow is all I have to say on their stuff. WOW.It's when we start considering the supporting characters that problems begin to show. Marina and Em are the only female characters to do anything of importance; the others are there to be the stereotypical motherly Mexican maid whose troubling role is never touched on despite class and social commentary elsewhere, be heartbroken, or be characterized as stupid and shallow to make Marina/Em look better. In contrast, most of the men in the novel (a male-heavy book to begin with) are the ones taking action and progressing the plot. That poor representation and use of female characters really put a damper on the thrills.The science also ended up becoming a problem. Most other reviewers who have gotten to it at this point seem to understand what is going on, but as someone with no clue about science, I was lost. The real test of a sci-fi novel is for someone like me to read it and understand what the book is going on about, but All Our Yesterdays fails that test pretty horribly. All this talk of sentient time and shadows of a person coming back to keep a dead person dead went far over my head even when a character explains it using what he calls small words.If I wasn't confused enough already, the ending took what little I did get about the science and threw it out the window like it was going to explode. But if did-- then C should be-- How did C-- But A is-- AUGH! *brain explodes* There may be holes there and there may not, but because the science was still so unclear to me, it's a jumbled mess of something.And yet despite the scientific mumbo jumbo and female characterization issues, it's hard to really dislike it. It's simply too much fun as a thriller and a great way to spend a day! For that, I'll keep an eye out for other books Terrill writes. If those two core issues are fixed or removed in future novels, there's no doubt I'll fall passionately in love with it! But for now, I'll simply keep crushing on All Our Yesterdays and keep it from the book because I know we're simply too different to fall in love with each other.