I had heard a lot about Brugge before I went there and was not disappointed in what I saw. There were a lot of other tourists there but if you just go off and find some little back roads and canals and you seem to have the place all to yourself.
The medieval centre is well preserved and contains some fantastic buildings, including the bizarre looking Belfort (which incidentally is part of another UNESCO site, Belfries of Flanders and Wallonia) but it does offer some of the best views over the city.
I was a little disappointed in the main churches, the Onze Lieve Vrouwkerk contains the only sculpture by Michelangelo outside of Italy but this was made a little hard to stomach by the large crowds and piped ambient music that really detracted from the atmosphere. The Heligbloed Basiliek again was filled with tourists and a continues announcement asking for donations which made it feel much more like a tourist trap not a place of pilgrimage!
On the plus side the Groeningemuseum was very impressive for its collection of Flemish Primitive works! Also the beginhof is quite nice and yet another separate UNESCO site so that is three for the price of one!!