Anyone use Sharkbite copper fittings?

I saw these things in Home Depot, they are a copper coupler that locks in place like the fuel lines on a fuel-injected car. I'm not sure if I want to spend $5 on a fitting but sometimes I get in a rush or have to go somewhere before all the water is out of a pipe that needs to be soldered, and in those instances they would be easier. They say that it will work on wet or dirty pipes but I'm a skeptic.

I have used them myself and sell a bunch of them in the hardware store where I work. They are great in tight spots where you might not want to put a torch to. Watts also makes a plastic version that work great, you can use them on CPVC, copper or PEX.

We use a lot of that stuff at the plant and also a RIDGID Pro-Press system for copper plumbing. The stuff is pricey and easy, however I prefer to have threads and sweatted copper in my home.