Personally...

I found The Last Time We Say Goodbye to be really well done.  There were some (just a few, reviews for this book from users have been really positive overall) that felt it was predictable and that the main character, Lex, was very unlikable.  I didn't feel this way at all.  I didn't think it was predictable and I liked the element of faith in there, albeit very small, but it was very realistic.  It seems like sometimes authors have an ax to grind when it comes to faith, either way, positive or negative, but the approach to faith and love and science in this was, I thought, very realistic and appropriate to Lex's experiences and age.  I really liked this.