My dog insurance was doubling each year and this year reached close to £150 per month (Tesco) (our dog is about to turn 12). It is now just over £30, even after full disclosure of past treatments. We considered not insuring him at all but didn't really want to risk that so this came just at the right time.
It seems that the main insurance companies know that most of us are not prepared to see our pets uninsured and know that it's difficult to move them across to another company.
I can only give 4/5 at the moment because obviously time will tell, if/when it comes to a claim.