I never forgave Mary Stewart for explaining away all the magic in her novels...this does similar, Myrddin is a very smart trickster and storyteller not an actual wizard, but "Here Lies Arthur"'s magic lies in the telling of the tale and the concrete characters. The re-jiggering of the old tales is quite imaginative. Myrddin is a pragmatic athiest, Arthur is a shrewd, stubborn, pig of a warrior (except in Myrddin's retellings of his exploits). The narrator Gwynna/Gwyn (she dresses as a boy for a fair piece of the novel) is real and engaging. At its character-driven core, it's the story of a father and his adopted daughter/son.
If you have young adventure readers...boys or girls ages 10 to 14...this is an excellent pick for them. Fantasy readers might not love it quite as much (the whole no-real-magic thing) but they'll still like it. It's worth a read by big people too! I passed my copy on to my dad (who's in his 70's and he loved it too).
Oh, and in case you ever need to break into a castle surrounded by a moat in the middle of the night & you want to be disguised as the king: "Ahn'hal Nathrack Oothfas Bethode Dah'hee El D'invey" (my spelling might be a bit off, should still work if you say it right...)