Karratha resembles what it was originally established for in the 60s: to accommodate the processing and exportation workforce out of Dampier and the surrounding mining communities.
While it is a large town with one of the bigger shopping complexes in the Pilbara there isn't a great deal to do otherwise. We used Karratha as a overnighter. While there we visited the surrounding towns and found some of them to be much nicer (Point Samson for example). I visited Karratha 12 years ago and it has grown since then, sporting a new leisure center with swimming pool, library and sporting facilities. However, it is still home to a large number of mine workers and the bulk of the traffic and industry reflects that. Not the type of place I would recommend for a holiday but worth having a look. The staff at the Visitor's Center were friendly and helpful.