Hello, adult female Aspie here.
Firstly, I fundamentally disagree with the way that Asperger's and autism have been lumped together - my life experience as an Aspie - in the sense that I have a job, a relationship, hobbies etc is very different to that of somebody who is non-verbal or suchlike, so I don't think gathering ALL autistic spectral disorders under one banner is helpful to neurotypicals. As we say, if you've met one person with autism, you've met a person with autism.
Personally, I think of autism as a difference, rather than a disability or a disorder (it's absolutely f*cking NOT a mental illness - and apologies to those who suffer from mental illnesses, but you wouldn't say that cancer and a broken leg are the same things, would you?).
However, autism exists on a spectrum (the clue is in the name), and parents or carers for autistic people who are non-verbal and so on would say it very much is a disability, in the sense that it affects their very basic quality of life.
Many people with autism (please note my choice of language here) have co-morbid mental health conditions such as depression, anxiety, ADHD etc, however there is no evidence to suggest that autism is causative, rather than correlative.