Well if (big if) you can ignore the fact that the whole place looks as
if it was planned by some Eastern European Communist Government then
actually it's not a bad place to live.

It's pretty safe compared to London, good shopping, very good train
service and even on the stopping Virgin trains (mostly from Brum) you
can usually get a seat.

Compared to London quality of life will be much improved, especially if
you have kids.

Also, I would have thought selling a London property in echange for a
Milton Keynes one could a mean a significant upgrade.

One word of warning though the M1 is hell on earth.