I've had a couple of them in various sizes for about five years or so. They work very well in a number of situations where a regular socket extension puts the ratchet in a knuckle busting position.
I like to use them to remove header bolts from cylinder heads. On my SVT Focus I'm able to rotate the ratchet handle 360 degrees when pulling header bolts/nuts.
They are also helpful to remove bolts from water pump pulleys etc on the belt drive set up on cars where you would normally use a wrench.