I explored it for a little while just because I'm curious about anything to do with virtual worlds and virtual reality, but the impression I got was that the majority of Second Life users were interested only in cybersex.
If that's your thing, Second Life can be great fun. If not, beware!
I tried it just because I was curious. No one asked my to have cybersex (I'm not into that anyway), but overall its pretty boring although watching the ocean and sunny sky & listening to birds chirp in certain places is relaxing.
Yeah, there is a lot of sexual content there, which I don't care for either. I just tend to avoid it when I can and go to my favorite places to spend time with friends, like an island called Serenite. I also like building things from time to time, so that's kinda fun too.