First of all, I am excited to own a signed copy of this even though I've seen signed copies in every bookstore I've been in all month - everywhere from Fort Mill, SC to Jacksonville, NC. I know there was some confusion and people received copies of the books before its release date, so I think he might have taken advantage of the accident.
These characters were incredibly tangible. John Green's characters always are, though he can recycle them a bit. Looking for Alaska and An Abundance of Katherines, for example, have extremely similar dynamics between protagonist, love interest, and best friend.
Like with Looking for Alaska, this is not a book that affords you the luxury of blissful ignorance. It promises to be a loaded gun, a tearjerker in the sense that it's completely unfair. This probably isn't for everyone.
But in this subject matter, he wrestles with questions that cannot be answered. For example: Should a terminal individual expand themselves and soak up life and touch the lives of others while they still can, or is more ethical to minimize the devastation of death?
I'm really glad he refrained from answering it - or rather, I'm glad he answered yes to both sides, in a way.
He's a wonderful author, and I'm not going to fault his stars. Even though I don't usually star things, he gets five.