I second the ICEE comment. Those rock. Probably the best thing about K-Mart.
K-Mart kinda dug itself into a hole in the late 80s/early 90s when they tried to shift their focus from being a discount retailer (comparable to Wal-Mart but perhaps aiming at an even lower-class consumer) to being a classier discount retailer (comparable to, say, Target). See, when I was in elementary school and junior high school, K-Mart kind of had the reputation of being a store that sold cheap quality goods at cheap prices (blue light specials and whatnot). Unfortunately, those kinds of mental associations are hard to get rid of. When K-Mart tried to shift strategy, they alienated at least some of their existing customers while failing to convince the Target-type audience that they were worth a second look.
I rarely shop at K-Mart these days. Doesn't help that they closed the two stores closest to me but even before those stores closed, I rarely went there. In general, I found their prices to be higher than, say, Target or Meijer both of which where closer. IMO, though, their K-Gro brand lawn fertilizer is pretty good stuff and they're usually the only place in town that has the large bags of Hyponex potting soil so I'll still shop there for that.
I also second the opinion that K-Mart stores are generally dirty and the isles are narrow. About like a "regular" Wal-Mart store (the super Wal-Mart stores, on the other hand, have nice wide isles...and they sell Michelena's pizza's for $0.88! Damn shame those things have almost 500 calories each).