I don't have too much experience with fantasy novels other than children/pre-teen books (such as Cloudy with a Chance of Meatballs; James and the Giant Peach; The Lion, the Witch, and the Wardrobe; etc.) I've never read the Harry Potter or Twilight series and I never read The Lord of the Rings until this class. It wasn't that I disliked fantasy novels, it just wasn't my favorite genre. The point I'm getting at is that I had very little background knowledge of fantasy novels when I read Armitt's criticism, but even I could tell that she wasn't doing a good job at it.
It seemed to me like she was grasping at straws and she twisted plot points or themes from her sample novels to prove her ideas correct. To me, this doesn't seem very professional and in doing so she loses her credibility. Also, like I already said, I know very little of fantasy novels so when she went off on these examples from books I've never even heard of, she lost me. Unless a reader of her book is an avid fantasy reader they aren't going to get most of what she is trying to say.
While I was reading her book I found myself thinking OK, could you put that in layman's terms for those of us that don't know fantasy fiction well and/or aren't English majors. I know that her intended audience probably was fantasy lovers or English majors, but my high school English teacher always told us that you have to write to the "invisible naive." Which means you have to write it as if the audience has no idea what you are talking about, which she didn't do.
Armitt's criticism didn't change my mind about fantasy fiction either way. She didn't make me hate it or love it. My opinion is pretty much the same as it was before, neutral.