Idylls of the King is a poetical reworking of the classic tales by Tennyson. It is absolutely breathtaking in its prose, lyrical, but coherent. Flowery without being polluted. It certainly helps to be familiar with the lesser known tales of Arthur's court (such as Balin and Balon) otherwise the reader may have a more difficult time understanding the work.
It really pulls at your heartstrings. You really come to hate all the women of the court, Guinevere most of all. How something written so long ago, about a tale even older, can still put so strongly at your emotions is truly indicative of how marvelous and passionate this work is.