I got digital prints from Shutterfly today and found them to be massivly better than prints from Snapfish.
I found my prints from Snapfish to be washed out, and to have color distortion around edges. I haven't tried the default Shutterfly settings, but they do let you turn off all pre-processing, which is what I did.
Here is a comparison of Snapfish (left) and Shutterfly (right). Note the washed-out snow on the ground and the chromatic distortion around branches and rocks in the Snapfish version. The original image is here. I know who's getting my money in the future.
Also, why can't digital photo printers send you a calibration print so you can tune their color adjustment to match your monitor? Why don't they print photo metadata (e.g., exposure information) on the back?