I used one for 3 years. I was glad to have it and have the ability to home test. That's much more preferable to labs and offices any day.
However, I had problems with the built-in battery with mine that eventually caused me to get a new machine (the INRatio). It wasn't unusual to have to run 2 or 3 tests with the ProTime before getting a reading due, to air bubble errors.
If you are free to consider other types, I would recommend checking out the INRatio. It's 1/2 the size of the ProTime. The blood collection is much easier, the strips are less expensive and it operates off of AA batteries, or an AC adapter you can purchase.
I know we have members that really like their ProTime. I just fine my INRatio much more simple and convenient.
Coagucheck also has a small unit now. I don't know much about it, other than it looks similar to the INRatio. It's called the Coagucheck XS.
My main recommendation is - if you can home test - do so, regardless of what machine you get. It's much more convenient and studies are showing that those that home test have more stable INR's with less incident than the lab tested population.