It's a fabulous groundcover in my daughter's garden in Salt Lake City. In the spring when the tulips and daffs come up from under it, it's just lovely. If the weather stays cool, the late tulips coincide with the vinca flowers sometimes, too.
Since it is basically a desert there, we control the spread of the vinca just by not watering. It will go as far as the irrigation goes, then stop. I put in micro-irrigation so that we can really control where the water goes very well.
Any good groundcover needs to have at least a bit of an invasive tendency, jmho. Otherwise it won't do its job of covering the ground! So you should expect to do some control measures, and be careful not to let it 'escape'.
