Hahn itself is a quite plesant little village, but the transformation of the old USAF base into a commercial airport has been an interesting journey and why the place is now well-known.
Ryanair is still by far the biggest customer of the airport, and is responsible for the massive growth of an airport that is still a 'gateway to nowhere'. Marketed as 'Frankfurt Hahn', (despite the fact it is miles and miles from Frankfurt) few in Germany throught that Ryanair could make a success of it. They argued that it was too far from the major city, and transport routes were very weak. Even legal challenges over the use of 'Frankfurt' were mounted.
They seriously inderestimated the German (and indeed European) love of a bargain. Ryanair now fly to almost 40 destinations from the airport, with more in the pipeline. They have also been joined at the party by Wizz & Iceland Express.
If you have a long wait at the airport, you may be out of luck. There are some restaurants and a couple of stores on either side of the airport, but nothing too exciting. There is also some internet terminals on the second floor, but last time I was there (Aug 2005) they were not functioning. If the weather is nice, you could go out to the second floor balcony and watch the planes take off.