I'm glad I re-read this one in particular because we get the description of Haymitch's Games in this one, so they'll be fresh in my mind for Sunrise on the Reaping. Also all of the hints we get about his past seem devastating, so I'm sure that book will also be devastating. But also, when is a Hunger Games book not devastating? 
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This is a lot of people's favorite book in the trilogy, and I can definitely see why. It drives the story forward in a way that a lot of people weren't expecting. I still remember reading this for the first time and being absolutely shocked; I read the entire book in one night. Having that cliffhanger ending was the worst at the time, because it's such a great ending, but you need to know what happens next. Very much like the Scythe trilogy from Neal Shusterman. They both definitely have you hooked.