I am a former State Farm customer who switched in search of a better rate. However, with eight years experience with State Farm, I feel I can speak to my experience with them.
I found State Farm to be a reliable insurer that regularly communicated with me through the mail and phone. I thought they were a good insurer albeit a bit expensive. They also are rated highly within my state when it comes to car repairs and the like.
I was jilted by them when they raised my rates because other drivers who own my vehicle were deemed unsafe (meaning everybody's rate who own my car went up even though I am a safe driver).
I also was shaken when I was told point blank by my insurance agent that I couldn't lower my limits because other people in my household have higher limits. This is bogus information as far as I can tell because we've had different cars at different rates with them before. However, they would not allow me to change the insurance rates on my personal policy to be more affordable so I told them goodbye.
Nonetheless, I appreciated their safe driver discount, accident-free discount and their multicar discount. They also have a multi-policy discount if you insure your home and car(s) with them. These discounts amounted to about $200 in savings. I would hate to think of my insurance rate without them if I stayed with State Farm.
My other criticism of State Farm is that my local office does not offer the ability to contact State Farm at any time of night -- i.e. no 24/7 office hours. Their payment options include billing by mail and also online payments.
I feel happier that I switched, but I would say that if you are looking for an insurer, State Farm is solid in my book.
NOTE: Claim processing speed rating not rated due to lack of use. (No claims made with this insurer)