I have to disagree here; people diagnosed with Asperger's who have developmental delay are misdiagnosed, because the diagnostic criteria specifically exclude people with developmental delay from the AS diagnosis.

However, I do disagree with this exclusion, because it's plain to me that having developmental delay shouldn't automatically mean you should be diagnosed with PDD-NOS or autistic disorder instead of Asperger's. Someone with all the traits of Asperger's (autistic with no speech delay beyond what would be expected due to a general developmental delay) should be diagnosed with Asperger's whatever his IQ happens to be. But then, as Shichi mentions, all of that should be irrelevant once they merge the spectrum, which I think will be good because the diagnostic categories as they are aren't actually very useful to doctors, whereas "autism" tells them all that a label can tell you about such a diverse disorder.

And, yeah, it is a "disorder". Disorder is just a name for something that causes impairment, and autism does that. It often gives you unusual skills in some area or another, too; but it can't be diagnosed without that impairment.

The words I do object to, though, are "disease" or "illness", because those are false. Both imply that the condition is something out of balance, away from health, and that the goal is to return to the norm; but that's not the case. Autistic brains develop differently, but they are healthy; and the goal with autism isn't to return to some norm that was never there to begin with, but to learn skills and coping strategies to deal with the mismatch between your neurology and the way the world is structured.