Good for Mike. I'm sure this will be met with much hand-wringing and doom and gloom from certain people, but if you really step back and look at it, which coach has had had more success MM since he started coaching the Packers?
If you go by SB wins, which I think is the most logical measure of success, only Tom Coughlin has had more, and his Giant's have been even more up and down than the Packers. A handful of other teams with 1 SB win each, and the prototypical Brady lead Patriots and Manning led Colts/Broncos have combined for a 1-3 record in superbowls (that one win being the Colts over the hapless Rex Grossman led Bears).
Say what you will about losing early in the playoffs. Recently history shows that getting to the dance is the most important part, with neither the Packers 10-6 team nor either of the Giants teams being world-beaters. Its much more important to get there and get hot at the right point.
Mike McCarthy's teams consistently get to the playoffs and have one SB win in recent memory. Thats more than you can say for nearly all other NFL head coaches.