To be honest, I had high expectations of this, it being written by Rosemary Sutcliffe, but I was somewhat disappointed. One of my favourite books of all time, since childhood, is her re-telling of Tristan and Iseult. I also loved her take on the Arthurian legend. If anyone can put flesh on the bones of an ancient hero and make him come alive, Rosemary Sutcliffe can, or so I thought.
I have read the Fenian cycle of Ireland's mythology. I have also read Lady Gregory's version of Finn mac Cool's story. Rosemary has just repeated these, adding no insight or originality of her own, which surprised me. In fact, she left a lot out. I think she could have done so much more.
If you know nothing of Ireland's mythology, this book would be a good place to start. It's written in an easy, accessible style, yet retains much of the character of the old tales. But detail is sparse, and there is no character development. If you want to know more, search online for the four mythological cycles themselves, or read Lady Gregory's book, 'Of Gods and Men' for a really fascinating view of what life was probably like in ancient Ireland.