Which of the three books is my least favorite? Well I hate to go along with the status quo, but I, like most others, have a major problem with the last book, Mockingjay. Since I have to used specifics to back up my intense dislike, the point I will focus on is Suzanne Collin's use of pacing.
In regards to the pacing of Mockingjay, I think that the book makes a sharp departure from the speed of the other two books. In The Hunger Games the total time elapsed during the book cannot exceed a month. The characters are introduced a short time before the Reaping, the reaping occurs, a week of training and showmanship before the games, and then 15 days in the arena. In Catching Fire, I can understand glossing over the Victory Tour, as the day to day events would not make for good storytelling. Regardless Collins still does take an entire third of the book to describe the Quarter Quell. When it comes to Mockingjay, it feels like Collins takes all sense of pacing out of the book. A war is fought day to day, not in quick decisive battles, but we only catch highlights while reading. We have whole months and operations just glossed over to move the storyline faster. The only time she slows it down is the actual assault on the Capitol, but even then it is rushed. Immediately after the assault, pacing is out the window again. The book and ends and the epilogue skips 15 years. This lack of pacing leaves you wondering what just happened and why, as the usual amount of exposition is not there.