Pfft you guys
I lived there for 5 years. It's different to other UK towns and takes some getting used to, but I loved it and would move back if I ever came back to the UK.
It's not a place you 'visit' like say bath or Cambridge. So i can understand why people who just pass through occasionally don't like it. But for living there, it's an extremely convenient way of life. Dual carriageways everywhere, right next to M1, near enough to Luton airport, near a decent train station, loads of green spaces. The residential areas are well thought out and generally have a lot of space, although some are better than others. You never ever have to worry about parking, and you will very rarely caught in a traffic jam and if you are it wont be for long.
Housing varies a lot in price. I'd say don't pay less than 200,000 k for a house (maybe a bit less in the current climate?) or about 850 pcm for rent. Generally housing estates in on the east side of MK are better, although there are some west of the station that are nice too. Caldecotte, Walnut Tree, Milton Keynes Village, Middleton, Monkston Park, Monkston, Browns Wood and Willen Lake all spring to mind as nice places in the East.
You have to make the effort to find the social scene, and that was the major downside for me. Rarely can you just walk down the road and find a pub/decent bar, you have to travel to the centre and so often that means a taxi or a designated driver. I rarely drink so I didn't care, would just drive around places. If every evening you want to go down to the pub/bar with friends, then this aspect of MK life will quickly become a PITA.
If you have specific questions ask away.