We bought insurance for our 2 new cats through PetPlan because it was the highest rated company on this site. After having the cats for a few months one of the cats started vomiting on a weekend and our vet couldnt see us so they recommended going to the emergency vet. We took the cat to the emergency vet and they found that she had eaten something that was blocking her colon. They recommended immediate surgery. The price for the surgery was ~$5000. If I hadn't had this coverage I would have had to put the cat down at that point.
Thankfully I had PetPlan Bronze with a $50 deductible and 100% reimbursement. Because of this I walked away with a net bill of about $100 for $5000 worth of vet work. Even better, when it was time to renew my policy they didnt even raise the rates on the cat that had the claim.
The only negative thing I can say about them is that they were fairly slow to pay (about 6 weeks to get a check) and that they were sticklers for having the vet(s) provide every single scrap of medical records. As long as you follow their procedures you will get reimbursed though. The down side to the long reimbursment wait is that I had to put all the money for the surgery on a credit card upfront. Thankfully that was an option for me. For others that could be a problem.