SL is a very large diverse place there are various cultural communities as well as social communities. Virtual world is a good description as you can be satisfied sticking to one area or exploring and learn and experience different stuff.
Many are interested in the social aspect but there also is a large creative group: The appeal of doing 3-D virtual virtual building is very satisfying, The in-world building components and controls are VERY easy to learn and with the SL scripting language you can make your creations animate, makes sounds, perform tasks, interact, etc.
If you search around you usually can find a community that suits your social and creative needs. While searching you might stumble into some really weird stuff too. I myself spend most of my SL time as a humanoid squirrel, either as 1 1/2 foot tall "tiny avatar" or a bit taller furry like one, and hang around the sillier communities - when on Second Life you don't have to live it like real life.