Would I reccomend it? No. I think it's too unrealistic.
But I like how Green made a point of how messy and desperate and unromantic death is. "Funerals are for the living," Hazel says. The things we say about death are more for ourselves than for the dying. I like that the author managed to be so honest and yet not unkindly so.
And I liked Isaac. He's pretty cool.

(The impact the book had on me might also be affected by the fact that I had the ending spoiled for me before I picked it up, so there was no surprise element.)