Wernigerode is located right at the northern foot of the Harz mountains; some residential areas and the castle actually spread out over some hills and in the valleys of the Harz. Thus the setting is very beautiful - and the town's architecture adds to the beauty. The historic centre, the old town, is fully of typical timber-framed houses, many of them colourful and with nice details like woodcarvings.
The current population is about 35,000 so Wernigerode is one of the bigger towns in the Harz region. The old town is quite lively, especially on days when a market is held. Tourism is a major business in the town but it is not overrun as other towns.
Although there have been several big fires in the old town over the centuries (the latest in 1847) and WWII didn't leave the town completely untouched the old town ensemble is very well preserved and beautifully restored/renovated. The sight that draws most visitors is located a bit outside of the old town, though: the castle. You can see it from almost everywhere in Wernigerode, more about it in my tips.
The other landmark that is sometimes visible, but often in clouds, is the Brocken mountain - highest peak in North Germany with an elevation of 1143 m.
Another highlight for tourists (and locals) which I unfortunately had no time for on this trip is the narrow-gauge steam railway "Harzquerbahn" that runs on several routes all over the Harz mountains, even up to the Brocken mountain, Quedlinburg (since recently) and south to Thuringia (Nordhausen). Fares are surprisingly inexpensive except for the Brocken tour.
If you want to experience an authentical German town with lots of timber-framed architecture, a castle and beautiful landscape then Wernigerode is the place to go. Not to forget that that there are a couple of wonderful hotels in town that make for a pleasant stay.