I have only had the insurance a few months, as my puppy is 6 months old. Trupanion has covered a good amount of my claims and they have been very prompt with payments.
The only negative I have is that at my first visit to the vet, I mentioned several things to the vet that are typical for puppies (she was only 11 weeks old and I had not had her very long). (eating, drinking too fast, scratching) From the vet's notes, Trupanion indicated allergies and digestive issues would not be covered, as they were pre-existing conditions. These were not "conditions" and my pup was never diagnosed with anything as a result of my just asking new doggie mom questions to my vet. So I think it is unfair to indicate certain things would not be covered without a formal diagnosis. However, there was an ear infection that they denied (stating this was related to allergies and was a pre-existing condition) and I appealed it, and with clarification from my vet that there was no diagnosis of allergies, Trupanian ended up paying the claim. I was grateful but feel that it was a hassle having to appeal and ear infection in a puppy.
Overall though, I have been happy with the insurance. I would definitely recommend it.