I've used State Farm for about 18yrs, and so far I'm pleased with their rates, coverage and service. I have both my cars and house insured with them.
Last year I had the windshield on the Jetta replaced...no questions asked. I recently had a rock the size of a golf ball destroy the current windshield. I called my agent, and within 10 minutes he faxed me the claim form authorizing the replacement.
OTOH, for every good experience, I'm sure there'll be someone who's not happy...regardless of Insurance Company.