I know 2 (former B.Sc.) students who claimed this condition through the office for students with disabilities. One of them literally had anxiety in that she never used the extra time, but knowing it was there was a huge help. The second one did it after seeing how easy the program was to abuse (I considered it myself but I was almost done).

I'm not sure how I feel about the classification, but I had never heard of anyone failing to get it who tried hard enough. Although it doesn't help turn a D into a B, it seems very useful when you're in the A range competing for graduate schools (which they both pursued).