Bought a 442 for the dark finish on the sights (have had poor experience trying to shoot all stainless sight guns in bright light) but now wish I'd gone for the 642. I carry IWB and moisture builds up between the frame and crane every day - if I don't wipe it down with a silicone cloth or oily rag at the end of each day it will start to rust fairly quickly. Other than that I love the (lack of) weight, which makes for perfectly easy pocket carry when I don't want to strap on a holster.
As others have said, they're not the most fun at the range, but I have other, larger guns for that purpose.