I've had my dog Preston on ASPCA health insurance for almost a year now and have no complaints. There's been a few small incidents (tick and foxtail removal) that have been partially covered, depending on the accompanying prescriptions, but ASPCA was really great to have a few months ago when Preston was hit by a car.
I can not stress enough just how important it is to have SOME kind of insurance -- I was able to focus on Preston getting the best care instead of worrying about the bill the whole time. ASPCA followed up less than a month later with the reimbursement check, cutting our $2,000+ bill down to about $500.
I was at first annoyed by having to pay the $100 deductible, but after seeing that most other insurances have a deductible per incident, the ASPCA plan seems a bit better.