I don't know your current rate, but the $250 might be a stretch. However, their ads of saving 15% or more is about par (The 15%, not so much the "or more" part).
I switched from Progressive to Geico. Progressive was increasing my rate by $10 every 6 months, and I had a clean driving record. I finally said,"No mas", and shopped around and landed with Geico. I also got a bit of a discount because they carry my homeowners insurance as well.