Living in the outskirts is much better, in my opinion.
My colleagues live in the center and have small, old, expensive apartments, with lots of city noise and pollution. Their rent is easily twice as much as mine.
Just be careful about the cheap flats though...
http://www.theguardi...nting-expensive
I've seen some friend's flats in the center of town that are not too far from this!
But, they're closer to the bars, restaurants, cafés - if that's what you want to experience, I guess it's better to be central!
I love living in the residential areas, with flowers and fountains in the roundabouts, waking up at the weekend with the birds singing in the trees! And no noise!