When I watched the movie, I loved it (mainly because Meryl Streep is a Goddess) when I found out it was based on a book, I basically ran to the bookstore to get it and I read that wonderful book in (less than) a day. It IS better than the movie. I never got why anyone said otherwise.
Personally, John Green's writing isn't the best. (Please don't kill me) but, this was one of my first "grown up books" (I know it's YA but I first read it 4 years ago, I was still really innocent-ish). I was certainly not expecting Alaska to die... but it actually changed the way I view things.