Gerhard Richter's designs have been christened 'confetti windows', made up of squares of vibrant colours - pink, yellow, blue, replacing the clear glass windows that made the cathedral look so washed out. They're thoroughly modern in one way - but in another, their abstract design reminds me of the Cistercian-influenced grisaille style you can still see in the 'Five Sisters' window of York Minster, or at Salisbury cathedral.
There's an excellent post on Art(h)ist'ry covering the controversy. Gninja points out that in fact, the window - made up entirely of geometrical abstract designs - is in the true Gothic tradition. Every Gothic cathedral is designed to incorporate a set of mathematical ratios; and gninja says that
"If [the Cardinal Archbishop] knew his own Cathedral a bit better, and the principles behind its construction, he might see Richter’s work as completely consonant with the structure."