We got petshealth insurance when we got our dog (now 8 yrs old) on a cousin's recommendation and are very happy we did. We did the $100 deductible, 80% of allowable cost plan and it has always been useful to us, since Mr. Big likes to get lots of silly little injuries. We don't have to make money a factor when deciding whether or not to take him to the vet for something that is clearly bothering him - if he needs treatment, he gets to go.
Reimbursement has always been prompt and fair (although as I live in a major city, my vets usually exceed whatever Petshealth deems 'allowable' costs). I did discover once they have a policy that says coverage will be denied on issues that carry over after the policy term renews every year, which was not awesome, but that is changing now (and I think it varies from state to state, perhaps) and now they have continuous coverage.
When we got our cat, we immediately got insurance for him, too. He doesn't have nearly as many little health foibles as the dog, so we use the insurance far less for him, but it's really good and comforting to know it's there. I always recommend health insurance for friends with new pets.