Nerdfighter training 101. Every book is a gem. You don't have to be a "young adult" to enjoy these books. A good story is a good story. I already own & have read each of these books, but I will get the box set just for posterity!
I second that. After reading the books i have recommended them to many family members of all ages and they all seemed to enjoy the books just as much as i did. & Like you, i have owned all his books and read some of them more than once, but they're in paperback, so sooner or later i was bound to upgrade. Finally the time has come! (: The fact that they're being released as a boxed set alone is exciting... not to mention two books are autographed and two come in brand new gorgeous jacket designs, I'M SOLD!! TAKE MY MONEY ALREADY, AMAZON! :'D