I use my Shimano SPD MTB shoes for all my riding (and MTB SPD pedals on both mountain and road bikes)....I find walking to be no problem once you get used to them. I also appreciate not looking like a roadie with huge noisy cleats on the soles!!

Tatfiend's info is very useful (thanks!).

I think Wellgo still makes a set of inexpensive pedals that have a platform on one side and MTB SPD compatible on the other so you can ride clipped in or not as you see fit....

Mark