This was a pretty solid 2 1/2 stars for me, but I'll attempt to explain why I ultimately rounded down. 
 16-year-old Miranda is our main character, and it's through her eyes we're shown the before and after impressions of her world through the exclusive use of diary entries. Miranda isn't entirely off-putting as a character. She's a fairly typical self-concerned teenager with a semi-obsessive interest in figure skating but an otherwise steady, level-headed personality--seemingly unaffected by the recent death of one of her three best friends. Her two remaining friends, on the other hand, have lurched to opposite sides of the coping spectrum--one turning hyper-religious, while the other turns to boy-hopping. And then the end comes in the form of a moon-moving asteroid collision. 
 The diary style was an admirably brave experiment, but it just didn't do it for me. The almost total lack of description made it more difficult to stay invested the world. I understand some think of this as a way to give the reader more freedom to imagine setting and character physical appearances however they'd like, but I don't seem to do well without a few visual hints. By the end, the only character I could actually picture in my mind was Miranda's mother--who I decided must look like a perpetually agitated Sally Field. Which is vaguely related to my next point... 
 On the whole, the insertions of political leanings were a bit intrusive. There were repeated references to Miranda's mother hating the "idiot" President, "almost as much as she hates Fox News." Add to that the mention that said idiot sitting President (view spoiler)[ found safety from impending doom at his ranch in Texas, and it had me groaning audibly and checking the copyright date. (Gee, I wonder who they could possibly be referring to... >.>) (hide spoiler)] Of course, by the end of this first book in the series, there doesn't seem to be any sign of the opposing political party swooping in and saving the day or otherwise lobbing the moon back into place. So there's that, at least... 
 The prose itself is clean and competent--well edited and not at all painful in flow. But I had the sense that Miranda's inner voice wavered back and forth from uncharacteristically mature to immature and back again--with less overall emotional growth than I would have hoped for given the extreme circumstances. It also seemed like the middle of the story sagged heavily, with never-again seen side characters and more tedium than tension. (There's no real potential concern for Miranda herself, as one is ever aware that she is writing these journal entries--and so logically she must still be alive and functional in order to do so.) I truly felt the plot could have been better served by mixing the diary aspect with some measure of 3rd person narrative. 
 While some have praised the realism of this post-apocalyptic scenario, I personally found it a bit difficult to swallow. (Although I'll admit my training as a first-responder, and experiencing the aftermath of both hurricanes and a tornadic incident that decimated the infrastructure of nearly half of the state I live in, has etched in me a unique perspective on what it's like to suddenly go from a 1st to 3rd world country.) The people who I've seen rise to the occasion in the most perilous of times weren't who I saw represented in this particular tale. In the final analysis, I suppose this reader has simply come to expect a different experience out of this sub-genre.