It is a piece of literature that is defined by older prose. The story is for children (to be read to or those with exceptional reading skills) and I enjoyed it a great deal, when a child. If you are looking for easy reading it is not the book for you. They style gets bogged down somewhat in old English wording.
I enjoyed this story and would read it again. There is a snippet of history in the tale, which may lead the reader to inquire about the war of the roses, and the Crook Back.
It is a familar story, a maiden hidden and prized. A young man taking a journey into manhood and his discovery of truth. The Black Arrow, who wields it and is killing the young man's friends?
So I guess if you think it isn't modern enough or not enough action then it would not be for you. Although, as I recall it had narrow escapes, battles, and milliary scenes. If you can suspend yourself and get enthralled by a simple tale, then by all means read. There is a part that lags, and that would be the ship sequence.