I love, love, love SPD. Love it. I have a pair of SPD sandals and a pair of SPD mountain bike shoes.
This pedal is great (and inexpensive, too), because you can jump on the bike for a short trip, grocery run, whatever. You won't have foot retention, but that's OK for a short trip. I'm thinking of seeing if I can install PowerGrips on them. That way, I'll always have foot retention. When I use cleats, I suspect dragging the PowerGrips on the ground won't cause a problem.