Lawhead, Stephen. Arthur. HarperCollins, 1996.
This was my third encounter with Lawhead's Arthur, and while I still think it pales in comparison to Taliesin (which is the first in the series and has some of the best female action scenes I've ever read), I was pleased to discover that a basic, if rusty, familiarity with the book did not impede my enjoyment of it in the slightest.
My first encounter with the series was solely for my own enjoyment; I revisited Arthur as a student eleven years ago and have now read it through the eyes of a teacher. Much of this book is perfect for students. The vocabulary is moderate, the story is very faithful to Malory's Morte d'Arthur, and the narrative is clear. Secular schools might struggle with Arthur's unrelenting faith and focus on God, but Lawhead is skilled: this comes only from Arthur's voice, and is occasionally greeted with caution and doubt by Arthur's friends and advisor. My hesitation within the context of a Christian school--and my only hesitation, really--is sparked by the language in the first two pages, which are an invective-laced frame narrative criticizing a ruler using language of illegitimacy. I am hopeful that the context surrounding these terms of disparagement will help the language itself pass muster.
As a novel, Arthur is lighthearted, light-handed, and light reading. I don't mean that the book itself is lacking in substance, but that the tremendous amount of research that has clearly gone into the novel appears effortless, to my great amazement. The presentation of God almost exclusively through Arthur's eyes gives the book's philosophy a balance that many modern novels lack. God is present, but he is internalized within a character and not used as a narratorial mallet with which to bludgeon the unfortunate reader.
Having recently begun re-reading The Once and Future King (my favourite Arthurian narrative when I was in college), I very much enjoy the soft touch applied to Merlin in Arthur. (I'll shortly be revisiting the rest of the series, as I can't currently recall how Merlin is treated in his own volume). Lawhead's Merlin is surprisingly human in his behaviour and psychology, and the idea that he has weaknesses does not come as a surprise. This is excellent not so much because of Merlin, but because it makes Arthur stronger by contrast; he is the figurative "golden child" (the novel is rife with golden and regal imagery). When Merlin is weak, Arthur is unrelentingly strong, and the failures of a great man make Arthur all but invincible in contrast.
In short, I think this book is entirely acceptable for readers twelve and up (I'd say ten but for the prologue, though I probably first read this at the age of ten and would have had no idea what much of it meant). However, anyone who wants to read Arthur should absolutely read Taliesin first, because it is wonderful in its own right and has fleshes out some of the brevity of Arthur.