A video came out on World Down Syndrome Day about the use of Special Needs discussing how the needs of people with Down Syndrome are not special (they need love, friends, and happiness like everyone else in the world), and therefore the term "special needs" should not be used. The video is really cool and features many famous actors with Down Syndrome. I highly recommend you check it out.
I think I still will be using the word special needs as the primary word when I describe my brother or other people with special needs. Though I think this phrase is not ideal, "disability" feels like a word for a malfunction instead of a person to me. I always thought that "special needs" was a good phrase because everyone has needs special to them, so the term "people with special needs" suggests these people are just being described using one aspect of the universal human experience. Unfortunately the word also isolates in ways I had not considered before, and it has the same effect on some people as "disability" does on my family.
Please contact me if you have any further questions on acceptable words, but honestly, I still have many questions myself on what the right word is.