I had an unassisted / unplanned birth my with last. I actually gave birth by myself. I was lucky in that I had a good, working knowledge of childbirth and excellent prenatal/chiro/acupunturist care before the event. Plus, I was deep into Hypnobabies so I didn't panic and it wasn't scary.
But no, I am not planning unassisted again. I feel I was lucky. I want an experienced midwife at my time next time who can handle the unknowns.