Throne of Glass, book 1, is a YA fantasy which appeals, in my opinion, to all ages. It centres on Celeana, who is taking from imprisonment and entered into a competition to become the King's Champion, ie his assassin.If this one has caught your eye but you haven't read Throne of Glass, go do so straight away!
Crown of Glass is a brilliant follow on book - it takes you straight back into Celeana's world. I felt no need to go back and read Throne of Glass, as it soon all came back to me. The world building and the characters continues to be fantastic, and I still love Chaol and Nehemia. The focus is more towards the magic etc which started to show in the 1st book, with some interesting concepts and ideas.
One important aspect for me is that Sarah focuses on relationships and friendships, rather than romance - there's no twilight type adoration (sorry Twilight fans!) but rather strong but complex relationships. I really cared about Celeana's various relationships, and my heart suffered throughout certain incidences!
This is a highly recommended series, with, I believe, a few more yet to come.