The Hunger Games

If I hadn't expected something like Harry Potter, I'd have given this a 3. I overestimated this book. It has a linear adventure plot, with a not-so-intriguing world-building. And it turned out to be one-dimensional, probably because it was written in the first person. Wouldn't it be incredibly difficult to built a world, in a book written in first person?
And, the plotline seemed to change to suit the interests of the main characters. The ending was obvious from the beginning. It's more of a children's book than YA. I don't understand the hype.