Now to the actual text. I loved this book. Whilst I enjoyed The Winter Queen, the main character was a passive force and spent most of the book in chains being whipped. Summer Queen's main character, Nelay, was one awesome surprize. She's got focus, drive and can kick arse with the best of them. She was so much better a character than Ilyenna in 'every' single way. There wasn't vast pages of moody angst or a fairly lame love interest.
Additionally, all the other secondary characters were good to read and actually stuck in the mind.
The plot is fascinating and the world building excellent. I loved that it didn't follow directly after Ilyenna's story and that you didn't need to have read the first book.
My only issue came with the ending as it mirrored Winter Queen too closely.
So, I heartily recommen Summer Queen, I'm now off to buy the other books in the series.