I have eaten there twice, but not with anyone who needed gluten free.
I think there are 2 reasons people have felt they were maybe not the most accommodating. The first is that the restaurant is not owned or operated by Disney. People have generally reported that the Disney chefs seem to have a more consistent approach to food allergies or intolerances. You should still be able to get answers from the chef, but the restaurants not owned by Disney may not get as many requests, so may not be as knowledgable.
The second reason is that the menu is rather small, so unless you are able to pre-arrange there may not be much on the menu that you can eat.
Not sure if this link will work,
but it is a pdf from the Disney website of the typical menu. . Most of the menu items listed would be a problem.
If you make an online reservation on the Disney website, there is now a place to add things like need for gluten free.
I have read that you can get plain grilled meats and seafood and should also be able to get salad served without dressing or with a dressing of just oil and vinegar. I have also read that the Creme Brullee is gluten free, although I do not know for sure. Hopefully, someone who has eaten there gluten free will reply and have more information for you.