I signed up with Trupanion two years ago (when it was still Vet Insurance) and have never once regretted my decision. My monthly payments are comparable (even lower than were I to go with anyone else), I chose not to have a deductable and they have been wonderful to deal with every time I've had a question, a concern or have had to make a claim.
The last claim I made was just this week. I faxed the insurance form and documentation in on Tuesday and not only recieved an email to let me know they recieved the claim, but also emailed me to let me know when it was opened and when a payment would be coming. It's been 3 days later and my claim has already been processed.
They are quick, efficient and most definitely the best (and only) choice to make when deciding about pet insurance.