Game Boy was recommended to me by a Volunteer Reading Mentor as a good choice for reading partnerships, and it's hard to disagree.
I think the reason it works well is that, rather than chapters, the book has levels just like a computer game. Sometime it is hard to read a book over a period of weeks, as happens with our reading partnerships, but with Game Boy it would be fine. The plot can be recapped in seconds and off you go on another exciting level.
Books as computer games is quite a trend at the moment; fast-paced episodic adventures to keep readers interested with lots of potential for sequels. I read a review of The Enemy that made this link, and I think the Maximum Ride books follow the same pattern. Game Boy was ahead of the curve, written in 2002, with two sequels, Game Boy Reloaded and Game Boy Galactic coming more recently.