I bought an extended warranty for my blazer years ago from warranty direct.
It more than paid for itself. The ball joints broke seemingly every year. It also paid for the transfer case, rear wiper motor and a host of other issues.
My out of pocket expenses for those repairs were next to nothing.

I also bought one for my H3 from gmpp direct. I used it a few times.

 

It is a gamble, a personal choice, your skill level and how much of your own work you are willing to do and the availability of a trusted local mechanic. I bought the GMPP Major Guard for my 2010 Alpha/Offroad. It expires in December. I have use approximately 3/4 of what it cost me with a Radiator replacement, Rearview Mirror replacement, and a problem with the 3rd Brake Light. I do very light mechanical items myself and usually rely on a former Hummer Dealer and my local Chevrolet Dealer for warranty repairs. I did seek out the best mechanic at both of these Dealerships and request them each time. I have a lot of friends in the profession, so by asking around your can find out who their top mechanics are. So far I have had zero issues with GMPP or the Dealerships. For normal maintenance, I have a local guy whom I trust completely for routine items and he will be doing all my work when I decide not to go with an Extended Warranty. Another advantage I see with an Extended Warranty, is the Dealerships (in most cases) will use OEM parts. That statement is up for debate, but overall in my opinion, the OEM parts are better quality. I can extend my current Warranty for another 2 years and 30,000 miles for less than $1500.00. I am deciding on this now but will likely do it. Sorry for the long post but this has been my experience. Good Luck