You are getting a very good coach. If he has 1 failing, it was with holding onto his DC and STC too long when they were underperforming. Otherwise, I think you upgraded. I'm betting he comes back more energized and will win a bunch of games for you.
Some of you guys know from me posting over the years that I'm a big fan of Aaron Rogers so I certainly give tons of credence to the fact that Mike had some great weapons to work with while coaching Green Bay.
You have to look at this though from a Cowboys fan perspective to understand why this is a nice move. Garret should of never been hired in the first place and it's been an absolute nightmare having to deal with his total lack of football knowledge over the years. We honestly put up with Garrett only because Jerry wanted to prove he was the smartest guy in the room and hired the next tom landry. It was all ego driven and a travesty for us fans to have to sit around and watch.
I think at this point in time where the Cowboys are as a franchise is they're built to win now. Mike was the best possible candidate available right now to jump in and get things on track. Personally I wanted Urban Meyer, but I can also see how that has quite a few negatives attached to it not knowing how long it's going to take him to figure out how to coach in the NFL.
Either way, I'm not under the impression that Mike is like getting Peyton or Bellichek, but I do know he is heads and shoulders better than Garrett whom never should of had a head coaching job handed to him in the first place. This is a good day for Cowboys fans quite honestly.