Being born and raised in Schleswig Holstein, the Northern most state of Germany, I was made to visit Haithabu already at a young age. It features prominently in the local history lessons and we were taken there in elementary school as a school trip. My main memory was that it was fairly mundane: a big earthen circle and grass meadows. The reason the site is featured so heavily in the curriculum of local schools is that there actually is very little else of "early" history in Schleswig Holstein.
Haithabu lay on the borders of the Holy Roman Empire of Charlemagne. Being strategically located on the Schlei, a bay on the Baltic Sea, it functioned as a major trade hub between the Holy Roman Empire and Northern Europe. For a time it was probably the largest urban settlement in Northern Europe, albeit that doesn't mean much. It is assumed up to 2000 people lived in Haithabu at it's peak. To put that into perspective, Cologne had 15.000 inhabitants, let alone Constantinople with at least 100.000.
The most interesting story I remember from my history lessons in elementary school is that the vikings sailed the Schlei westward where they would land their ships and transport goods and ships via land for 18km to reach a tributary to the Eider river. Via the Eider they were able to reach the North Sea. This way they saved themselves the long and dangerous voyage around the Skagerak. Nowadays the sources are not sure if only the goods were moved or also the boats. Personally I prefer the image of Viking boats being landed and then rolled across land.
Eventually Haithabu was disbanded and Schleswig on the the other side of the Schlei became the principal settlement of the area. So much so that the modern German state is still called by the town's name: Schleswig-Holstein.
Having visited as an adult a few years back I think mundane still describes the site quite well. Just keep in mind that at the same time Haithabu was built Charlemagne had the Aachen Cathedral erected.
Getting There
Take the train to Schleswig and from there either a bus or a 40min walk. Deutsche Bahn has the details.
While You Are There
There is an on-site museum showing a few of the finds. They also reconstructed some of the original buildings to give you an impression of the living conditions. If you have a car, you can also visit several parts of the border wall (Danewerk).
In addition you should visit the state museum at Schloss Gottorf to see some of the finds. Schleswig itself has a nice reputation and the church features and impressive altar piece. Last but not least, the Schlei is quite a nice bay, especially if you traverse it by boat.