I've got three of the new Pythons. Two SS, one blue, all three 4.2" barrels. I've never had a problem with any of the three. Two of them are well over the 1000 round mark. The other, my wife's, hasn't been shot a lot, but it's HER's. Don't try to tell her otherwise. (I have to check the S/N's to make sure I don't get hers.)
I had a fourth one, a very early one, S/N less than 2000, with a 6" barrel. I have a "thing" for 4" barrels but grabbed the 6" because it was the first one I saw. It was a great shooter, but the sideplates screws did come loose at about 800 rounds and the gun started to bind up. Fortunately I saw what the problem was, and tightened the screws myself, and was back in business in about five minutes or less. No more problems. I did sell that one, but it was because I found a 4.2" one, not because of any "problems" with the gun.
I really can't think of anything I don't like about them. I like the grips. The sights seem to be fine for me. I don't care about the third slot in the vent rib on the blue guns. I guess I don't care for the grooved trigger, but it's not awful. I started with a grooved trigger on a Model 19 that wore blisters on my trigger finger. These haven't done that, but I suppose my trigger finger has gotten tougher over the years.
The D/A pull on all three (four) of them is great. I say they just beg to be fired DA. I can't measure it, my scale only goes to 8 pounds, but it's smooth with no stacking. The S/A is a bit heavy at 5.5 pounds, but I don't use it, so I don't know if it hurts or not.