I have mixed feelings on book 5. Parts, I absolutely loved - including the structure. With the exception of the timing of the flashbacks, I thought the choice of pacing was really interesting. I liked the lack of resolution at the end; it made me even more hyped for the back 5. Szeth's character arc was intruded on by Kaladin's, a lot, but I liked Kaladin's enough it didn't really matter. Adolin's arc was generally really cool. Sigzil's was kind of boring and didn't make sense to me. Moash... I feel like he's a great foil to Kaladin. Kaladin. Not Sigzil as well. I thought the Spiritual Realm everything was interesting (Renarin and Rlain!!!! Ah!!!!! I also cried when Rushu started talking about gender), but disliked the whole Chana Davar revelation. In Rhythm of War, with Testament, I was starting to feel like it was a little repetitive, but at least that one felt well foreshadowed.
All in all, I quite liked book 5, and don't think any less of the whole series for it!