As someone who grew up watching Fergie's Man U and has been suffering in silence basically ever since he retired, I'm not sure how I feel about Mourinho taking over. I'm kind of happy and wary at the same time.
I mean, I always respected his record and admired the way he obviously built close relationships with (most of) his players. His Porto, 1st Chelsea and Inter squads gave the impression they would have run through brick walls for him. It seemed for a while that he would win and break records non-stop. But he never quite clicked at Real Madrid. And then that whole calamity earlier in the season, which resulted in Chelsea's worst league finish in years, was his fault and his alone. Yet it seemed like his arrogance had just reached a point that in his own mind he could do and say anything he pleased, without fear of any consequences. He was so obviously in the wrong, and his behaviour so obviously had an adverse effect on his team and their results, I just don't understand how he couldn't see that.
Anyway, I'm rambling. I can understand why the club have made this move. If he's used his down-time to reflect and learn from his mistakes, then Mourinho recharged and ready to prove he's still got it by taking Man U back to the top is an exciting prospect. If they didn't give him the offer he would have went somewhere else this summer without doubt, and then Van Gaal would have seen out his last year, probably without much of an improvement on the field, then retired. And this time next year we would probably be in an even worse position.