The Art of Toy Story 4 is a pretty good book when it comes to showing character designs, in fact it has almost 50 pages out of the 160 devoted to character design and developing the look for those characters. You also get some nice artwork from Tom Gately and his wonderful ability to capture personality and real life moments that we see day to day.
There are lots of environment and concept art as well as many pages showing storyboard sequences from the movie. There a even a few drawings from Josh Cooley the director, which if you don't know Josh, he is as funny of a person as it gets. He created a children's picture book parody called "Movies R Fun!: A Collection of Cinematic Classics for the Pre-(Film) School Cinephile (Lil' Inappropriate Books)". You can see his blog here - http://cooleycooley.blogspot.com/ and get an idea of the type of humor this guy has.
I give the book a 4.1 out of 5