My mom just purchased her house in May, part of the contract was the seller purchase a home warranty for her (it's an older home, lots to be updated eventually). The warranty purchased is from Fidelity. Well lo and behold, 2 weeks ago her AC went out, on a weekend of course. We of course have to use one of their vendors, the process is painful and you must have a lot of patience, however, everyone we have talked to on the phone has been very friendly and helpful. They were actually able to get the vendor out the next day (Sunday, and so far we are happy with them). We are still waiting on Fidelity to order the parts (they are actually going to replace the whole unit, so it's probably taking a little longer than say just some hoses or less major parts).
I truly hate hate hate dealing with any warranty company, and I feel home warranties are not necessarily something you need, but if you have an older home that has some big ticket items getting ready to need repair, it might be a good idea.
Would I recommend Fidelity, sure,...... of course we are not through the whole process yet, my mom's AC is not completely fixed!