I really like the smooth edge models. The MBS-26 steel gets sharper than almost any other stainless (seems to be comparable to some AUS-8 kitchen knives I've got). All my kitchen knives (I've got maybe 50 from 35 different manufacturers) will do a smooth job of shaving my arm, the Spydercos feel more like a straight razors than most of the others. It made me rethink my crowded knife drawer. The alloy is also harder and tougher than most kitchen knife alloys.
Personally I don't like serrated edges, and the Spydercos are no exception. It's easy to damage the teeth and hard to fix them. It's harder to sharpen the teeth than a straight edge. Spyderco bevels the serration on the wrong side.