Re-read completed 6/25/15: That was just stupendous. It was so wonderful to fall back into Maggie Stiefvater's writing and oh boy, does she really just get your feelings going.
This was an EXCELLENT re-read too. Having read the first three books and preparing for The Raven King in 2016, I knew I wanted to read it all again before the series came to a close. It was so, so, so great to have the knowledge that I learned in The Dream Thieves and in Blue Lily, Lily Blue while re-reading. Things make sense in different ways, it was so easy to jump back into the story from the beginning, and I already was so invested all of the characters.
If you love this series, you MUST re-read the books. It's an absolutely wonderful experience.

Re-read completed 10/2/17: Perfect, of course. It's even MORE interesting to re-read after completing the whole series and knowing how it ends. It's funny how many answers are given to the readers in the first book but without knowing where it's going, you don't realize that's what you're looking for.