I have Asperger/am aspie myself and I participate quite a bit in asperger-themed chatrooms on IRC. On many of them, people use the word aspie extensively. I do not recall anyone objecting to the usage of this word.
Are there people who dislike the word? Certainly, yes.
Is it a slur? No. If there is a community that is disliked by many Asperger/Autistic people, it would be the people from Autism Speaks and others who consider Asperger/Autism as something to be ”cured”. Those people (sometimes referred to as curebies) do appear to use the word Aspie, but as far as I've heard this has not led to Asperger/Autistic people to dislike the word Aspie when used by non-Aspies.
A different word for Aspergers that is considered insulting by many would be assburgers.