I've never had a pair with zippers - but I had a pair of slip on tennis shoes. I bought them because I was sick of having shoelaces that seemed to expand the longer I wore the shoe (yes, Reebok, you know who you are). The bad thing was, due to the fact that the hole for your feet had to be higher and smaller than average to prevent them from being loose, they started to break down around the top from pushing my feet in and out. Other than that, they were comfortable and convenient.

These are simply canvas sneakers that are zipped up rather than laced up. I don't have a pair right now, but it would seem to me like they would be very convenient for kicking back or running errands.