I read an interview with the author that this started out as more of a young adult title, and the romances in the book back that up. They are completely appropriate for middle grades, but the depth of the emotion and the expected length of the relationships made them seem more like high schoolers. Since this reflects the characters in the original, I think this is a good choice. You can't very well have Guinevere and Lancelot date only for two weeks, which is about average for a middle school relationship!
Hand this one to readers who can't get enough of this era and have already read Gale's The Wizard's Dog, Yolen's Sword of the Rightful King, Reeve's Here Lies Arthur, McKenzie's Guinevere's Gamble, Crossley-Holland's The Seeing Stone, and everything by Gerald Morris!