I carry everyday a 642-2. It's been reliable since day one. Carries very well and even rides in a pocket holster surprisingly well for a revolver. It's a little stiff when new however it loosens up after putting a couple hundred rounds thru it. I carry outside the waist and my holster is a Bianchi Lightnin' 55. I did replace the original stock grip with a Pachmayr presentation compac grip which fills the hand even better and makes shooting more enjoyable and functional.

Some people mention about the finish wearing off. I have not had any issues however I don't use harsh chemicals on any of my guns. I just shoot them down with either Ballistol or Rem oil in a spray can, scrub with a toothbrush and wipe off. I do however have a friend that still carries his 642-1 that the finish is completely worn/flaked off. It's a aluminum alloy frame that's painted & clear coated. His has worn thru and the clear coat is gone. Looks ragged. But the gun still functions beautifully. Just don't use hash gun cleaning solvents such as Casey Gun Scrubber or similar and you'll be fine.
Mine has the internal lock that some people moan about. To me it is a non issue and in no way shape or form affects the function or reliability of the pistol. besides, the 642 is probably still S&W's top selling concealed carry revolver.