Thank goodness, we're not in that position anymore. DH worked a job (for FOUR years!) that was 100% commission. He did well, better than most in his company with that position, but it is not a good situation. If something happens, you're in a heck of a lot of trouble.
He did get vacation pay (average of what he made in the past 6 weeks), but that wasn't good. That pay covered the week he was gone, but by not earning pay that week, it affected what was to come. He couldn't be out drumming up new business, which was highly important. If he was sick, it was basically a payless day. And he had to work constantly. Sunday through Sunday. From 6 am to 11 pm. Yeah, there was some flexibility, but it was still constant work. He had to drop everything when people needed certain things--and he had bigger boundries than most his co-workers.
I really don't recommend it. He left and took a different job that was 80% commission and a small base pay. That had it's problems too. Thankfully, he completed his MBA this last semester, got a job with a generous base salary and a great commission/bonus structure to boot!