I thought that the change in Michael in GF3 is too great but when I watched the movie with my mother she said it does makw sense, that people are becoming much softer with age. Still it is completly different Michael than we used to know in GF1 and GF2.
Take for example his attitue to Kay: Michael of GF1 and GF2 would have never forgave her.(personally I think it was a way to keep her in the movie...)