Don't be daunted by the page count--with tangential poetic structure and lots of white space, this is actually a pretty quick read. 
 Quick, but far from painless. 
 Full Disclosure: I started reading Crank, but finished most of it as an audiobook. The audio version may have been a mistake for this experimental sort of prose and structure--as it struck me with the feel of 4 and a half hours of beat poetry. The epic verse style is such that it proved difficult to determine what was thought and what was dialogue. (Also...the voice they picked for the main character made her sound like an exceedingly narcissistic valley girl. >.<) 
 I'm glad I skimmed the reviews and caught that this book was based around the author's experience with her daughter--that changed my approach perspective completely. If I'd continued thinking it was fiction, I might not have made it through. The unfolding of the plot was that dismal. But as it stands, I ever feel I owe a different dept to a premise based in reality. And I have to concede a base sense of respect for an author who is willing to depict her own daughter, as well as herself, in a deeply unflattering light. 
 Kristina was a difficult character for me to connect with from the very start. Readers are given the vague impression that she's considered a "good girl" and a smart girl, but even before her insta-addiction to Meth, she comes across as simply selfish and entitled--with a whopper of a daddy complex. No goals or dreams for the future (just a vague sense that she has potential), and no relatable interests mentioned that might help round her out and make her more sympathetic. As a result, this reader felt pretty detached from the situation: watching an unfortunate human train wreck in progress. 
 I've noted many reviewers getting defensive over this book, and I don't wish to be misunderstood. I read Crank in part because I hoped it would give me more insight to several friends and family members who have dealt with (and continue to deal with) substance abuse and addictive personality traits that keep them a slave to one chemical or another. My personality and body chemistry is such that my vices lie elsewhere, and so I saw this as an opportunity to gain a more personal understanding. Unfortunately, that didn't happen. Kristina seemed to lack a capacity for guilt even before she began her spiraling descent into addiction. A weakness is easy to empathize with--an underdeveloped conscience is not. 
 I wish readers were given something at the start to endear us to Kristina, before she broke off into her alter-ego and made a mad dash for self-destruction. Kristina seems nothing like any of the people I've known who struggle with addiction. Maybe because she doesn't really struggle--she dives headlong into it without resisting.