Penryn and the End of Days is one of the best book series, definitely top 10. The story in all 3 book flows effortlessly from one book to another. The whole story unfolds in matter of days. The ending is perfect, bitter- sweet as the tone of the book. A bit open though, we don't get answers for everything, but for me it works and it is certainly in the tone of the book. 
 Best parts of the book: 
 1.	I really like character evolvements (view spoiler)[. Penryn assuming leadership role, Raffe and Watcher, Paige and her pets. (hide spoiler)] 
 2.	Also the mythology is really thought through so it makes sense, makes story all more real. 
 3.	Writing style. It pulls you in from the first page. 
 4.	Raffe. We see a lot of him, even backstory for what happened with Watchers, why he doesn't know the reason behind invasion. 
 Really amazing book and great conclusion to an amazing story.