I love historical fiction, and this is a great read if you are interested in the Arthurian legend as a subject.
First, I must say that this doesn't really qualify as historical fiction since Stwart states that she used a notoriously unreliable resource for entertainment value. And it even strays from what I know of the legend from other "entertaining" sources (T.H. White and Sir Thomas Malory). BUT, where Stewart really excells is taking the legend and puting it into a frame that is explainable within modern thinking...i.e. Merlin is incredibly intelligent and understands herbal medicines. He doesn't use magic, per-se, but his highly scientific mind combined with the supernatural gift of foresight. So, having read the other books, it is really entertaining to see how Stewart explains the magical phenominon away.
Secondly, because she is changing the story a bit, I never really know what to expect, which keeps it exciting as well.
Told in the first person by Merlin, the story has a nice feel and tone...though sometimes a bit long winded and dry(the only reason I didn't give 4 stars).
The plot follows Merlin as he tries to maintain his anonymity and keep it secret that he is traveling to retrieve Arthur from his foster parents. Along the way, HE discovers the great sword that will show to everyone that Arthur is destined to be King. We see Uther as he withers from a wound to the groin more and more willing to make Arthur his heir, until finally he presents him his sword on the battle field as the British armies ward off the Saxon Hordes. It's pretty epic.
Overall, this was an excellent read.