Arrow's Flight continues Talia's story which started in Arrows of the Queen.
This book is probably the most solid of the three, thus a slight improvement compared to the previous part.
Still, if you're not a adolescent female with a My Little Pony collection, this probably is not for you.
There's some sexual (not very descriptive) content and even a gay (GASP!!) characters, but the story stays securely on a level that wont challenge more mature readers.