I used to use the platforms all the time while commuting to and from work. It allowed me to wear regular shoes. For longer rides I would clip in using my SPD shoes. Then last year I bought a pair of Keen SPD shoes that look like casual street shoes, so now I wear those to work most days. Since they clip in I don't use the platforms so often either. They are really only useful if you wear non-cycling shoes from time to time.

By the way... the casual Keen Austin cycling shoe? It's not bad as a cycling shoe, but not great either. It has a stiffer sole than the regular Keen Austins, but they are heavier and warmer than most cycling specific shoes I have worn by Shimano and other companies. This isn't so bad in Winter, but during the Summer months I prefer to wear cycling shoes that are a bit lighter and better ventilated. But for shoes you want to wear off the bike as much as on, they are quite nice. Very easy to walk in and the cleats don't scrape on most surfaces. My Shimano shoes are not as good for walking, and the cleats often scrape.

Sean