I've had mine for 12 tests now and I LOVE IT! I had the ProTime monitor for almost 4 years and sought a replacement because my battery was bad and the machine was in need of refurbishment. The INRatio is much much easier to run a successful test on. I have not had a blown test yet. I was always getting blown tests with the ProTime, mostly with Air Bubble error messages. This can get a little expensive!
The INRatio takes less blood. It's very easy to touch the drop of blood from your finger onto the little well. With the ProTime, you had to drop about two large drops of blood into the cuvette cup and then insert it into the machine. It was the dropping the blood into the cup that was the tricky part.
Don't get me wrong, I was very glad to have the ProTime machine because it was still, hands down, better than having to go to a lab or clinic to test, and my INR has been more stable.