My DH's childhood home was built in the 30's, and his mom had insulation blown in, sometime in the 80's. Then in the 90's DH & I moved into that house ourselves. It was a drafty house because all the windows were original (and falling apart) but overall fairly cozy. DH told me the house used to be freezing all the time when he was little; it was pretty comfortable for us. No central heat or air in that house.
Whoever did the job didn't do a great job of it cosmetically, though - the siding was wood shingle and they just cored out holes right through the singles and then plugged them with plastic plugs that they painted brown. By the time DH & I moved in the paint was chipping off of the plastic plugs and it just looked weird and cheesy.
I don't know what kind of material was blown in. I think they have stuff that is shredded fabric now, I want to say old jeans?
It'll definitely warm the house up but make sure you do your research. Ask for references, all that stuff.