I would have given this 3.5 stars if I could. Still waiting for that update... 
 I think I liked this book. I'll say, I was nervous going into it knowing that it was about two teenage girls. I worried that the tone would be very YA - teenagery, whiny, lacking in maturity... And with the book revolved around drugs, alcohol, and addiction, I thought those issues would only be amplified. I was pleased to find that the tone is much more adult than I expected. I'd still consider Marlena a YA novel more than anything, but all of those qualities that I find so deeply annoying about YA were kept at bay here, so I still took pleasure in this story. 
 But the issues I had were frequent and obvious enough that I couldn't give this book any higher rating than 3.5 stars, and I ultimately had to round down because an official 3-star rating is less deceiving than a 4-star rating. 
 The first issue I had was the choppiness. There are so many comma splices and incomplete sentences that it often became difficult for me to follow the story. The structure reminded me a lot of how I used to write in high school and early college; at the time, I loved it, but as I've gotten older I see how difficult and unpolished this style can be. And along with structure, transitions were poorly written. Though they're small, transitions are immensely important to flow, and it seemed like Julie Buntin just didn't care to give them much thought. She wanted to get on with the next scene. This flippant take on transitions often took me out of the story. 
 Examples: 
 * Ryder and Marlena pick up Cat from a bus stop, yet it's never clear that Cat gets in the car and they drive off. It took three or four paragraphs for me to realize Ryder and Marlena didn't park to wait for a bus with Cat and that it is, instead, merely a meeting/pick up spot. 
 * Then the three of them pick up Greg at a gas station. Greg gets in the car, and the four of them drive to a Taco Bell. However, the book simply says (and I'm not quoting verbatim, but it's close enough): "picked up Greg at a gas station. He got in the car then we went in Taco Bell." Well did you have to drive to Taco Bell? Was the Taco Bell attached to the gas station? If so, why did Greg even need to get in the car just to get out and go in to Taco Bell? 
 * Another time: Marlena and Cat are walking back to their homes from the jungle gym. There's discussion of continuing to hang out or separating and each going to their own home. And then it says: "then we went in." Never clear if the girls are still together or if they parted to their own homes. Again, another few paragraphs down I realize they did, indeed, each go home to their own homes. 
 This stuff seems minor, but when it happens constantly it becomes difficult to keep up with where we are in the flow of the story. The poor transitions also made it hard with dialogue for me to keep up with who was saying what. 
 The other big issue I had was the ending. It just felt very anticlimactic to me. I was expecting more excitement based on all the build up, and it just wasn't there in the end. Also, the whole meet up with Sal... The book starts with the planning of this meet up, so I'm assuming there will be a lot of meat here, but when it finally happens, it's glossed over and barely given the time of day. It was just so quick and unfulfilling. It seemed like Buntin wanted to bring this story full circle, so she thought Sal could be that anchor. But the execution is lacking, and when it's all said and done I'm wondering why this was even needed as it didn't add any value to the story. 
 Maybe the issues leave you thinking I didn't really like this book at all, but that would be misleading. I did like it, I think. I liked seeing the relationship between Marlena and Cat develop. I liked seeing how this unlikely friendship managed to become what it was. To see how unassumingly a decision leads to another decision leads to another. And I liked the suspense of the countdown to Marlena's death - frequent enough to remind me of the point of the story but not so much that I feel like it's being shoved down my throat. I just think the structure could have been better and the ending could have delivered so much more.