Zoe Gross explains why she is "Autistic", not "a person with autism":

I’m starting to think that when people say “defining yourself by your disability” they really mean “talking about yourself in a way that reflects the belief that your disability is not detachable.”

I was at a conference last summer at which Ari Ne’eman gave an introductory speech, and it fell to him to explain why ASAN uses identity-first language. One of the things he said, which I really liked, was “If I’m on a flight and the airline loses my luggage, I don’t arrive without my autism.” And I feel like this is actually sort of central to the difference between disabled identity-first proponents and non-disabled person-first proponents: they want the disability to be separable enough from us that we can hide it, pack it in a suitcase, and maybe, one day, be able to lose the suitcase forever with the help of a cure! Or, to use my earlier analogy, they want our disabilities to be like an action figure accessory that you can put on and take off, so that they can choose when to interact with and accommodate our disabilities.

Rachel Cohen-Rottenberg starts with a Facebook graphic that says this:

See the person not the disability

Rewrites it into this:

See BOTH the person AND the disability. Because there is nothing dehumanizing or shameful about a disability.

And goes on to on an insightful discussion of the ableism embedded in person-first language:

My rewriting speaks to the heart of the problem with person-first language and its insistence on turns of phrase like “person with disabilities” rather than “disabled person.” Such language betrays the assumption that disability renders one less of a person. If that assumption were not present, there would be no reason to foreground the fact that we really, really, really are people, and that one has to put the disability aside in order to see how really, really, really human we are. Of course, that rather problematic logic begs the question: How exactly does one pretend not to see a disability once it has made itself known? In most contexts, that would be called denial and, occasionally, delusion.