I purchased a pair of these, silver/purple, about four months ago.  Thought they were the most comfortable shoes I'd ever placed on my feet.  Being the summer, I didn't wear them much, though, as sandals are my preference in the heat.  That being said, I was very surprised to notice that on not one, but both soles, the gel part on the outer back sole, had come loose.  One actually fell off that day, with the other not far behind.  Needless to say, I was very disappointed as they are quite comfy.