I use clipless and it is a noticeable difference in regards to pedaling efficiency. Being clipped in makes it much easier to "pedal in circles" as opposed to mashing which is what you end up doing with platform pedals. Most commuters I see just have platform pedals or toe-clips (metal cage which hold foot in place) which serve a siimilar function to clipless. Another benefit of going clipless are the shoes which have stiff shoes, which makes the power transfer to the pedal more direct since your foot isn't bending or interfered with by excessive padding. There are of course other options like the platform/clipless pedal dendawg mentioned, or MTB pedals which have recessed cleats thereby making it easier to walk with than road shoes.