Shailene calls her co-star Ansel Elgort and our Augustus a "special dude" and a "nugget of life". She says Ansel blew everyone away at the audition and she talks a bit about the audition process they went through.
She also raves about TFIOS book saying she would have done anything to be a part of the movie, even if she was an extra.
She says the most important part is that they "actively listen to each other" and that way everything will evolve perfectly. She also mentions that they've already done some hospital visits and will continue to do them.
Check out the rest of the interview in which she talks about her latest movie The Spectacular Now at the source.