Recently a 25th anniversary edition of Desiring God was released. I remember my first reading of Desiring God as a new seminary student. It was a disorienting experience because Piper's basic thesis was something brand new for me. At first I completely rejected what Piper was suggesting. However, after much reading and arguing in my mind and a few fellow students I came to embrace the central theme of Desiring God as reflecting a thoroughly biblical paradigm. If you have not read Desiring God I would strongly suggest you do so.
Also, when you get a chance take time to listen to a two-part interview of John Piper conducted by Mark Dever in 2003. It's well worth hearing.