Sighisoara is one of those medieval towns that has you head scratching about it's inclusion as a WHS where many more impressive medieval towns fail. I can think of many in France and Italy that are more impressive but fail to get a listing.
It's nice and it's worth the trip, especially if you are interested in the history of Vlad the Impaler, as he was born in a large yellow house (a restaurant when I visited in 2012) in the pretty main square.
There are lots of little cobbled alleyways and typical Saxon buildings but it is quite small compared to many other similar cities (Bruges or Riga for example).
Combine the visit with a few of the fortified churches, as I did, and it really is worth the journey.