The walkability thing comes up every time a clipless thread is created. SPD cleats are not automatically more walkable. You also need the right shoe so that the cleat is recessed to make walking more natural. My Bontrager Circuit shoes I find are more comfortable for walking with my Look compatible cleats than SPD cleats. I also find that composite three hole cleats are not prone to the pedal creak that I had with my SPD pedals.
Also I read online how difficult clipless pedals were supposed to be getting used to and thought starting with SPD was a good idea. It turns out I just used a pedal for a few months that I didn't prefer. They were fine for road use as others have mentioned but overall I'm happier with my Look compatible pedals and cleats. I can go for a 50 mile ride and walk maybe 50 feet from the time I leave the house until I return so being able to walk better isn't a big issue for me. Your mileage may vary.
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"It is the unknown around the corner that turns my wheels." -- Heinz Stücke