Fantastic book, as always Sanderson delivers incredibly detailed worldbuilding, dialogue and characters and manages to tie it all up in an ending that sends shivers down your spine.
Most of the negative reviews are from people who can not stand the attention to the increasingly deep psychological issues of Shallan and Kaladin.
I'd say to these people: how could you NOT have issues when you went through the events those characters did?
Brandon manages to portray these issues in a very respectful light and also offers his characters a way out in the end with a huge feeling of catharsis from that.