"User Based" does not mean "high quality and immersive experience."
Second Life lets you create an avatar. However, this also means you don't have to be the "real you." As a result, SL has become full of trolls, griefers, and general "retards" (no offense to the mentally ill).
Not only that, but sex is running rampant throughout the Grid. I'm sure you're thinking of some busty blond, or big handsome man, but that's a mere fraction of the sexual acts. Ever heard of Bestiality? (not talking about furries) How about Scat Porn? Vore? Gorean? And that's not even the full list.
Perhaps the part of my experience that made me finally realize there is no hope for Second Life was when I joined the Brony community. You heard me right, Bronies. As in people who love My Little Pony: FIM. The pony sims are filled with perhaps the worst bunch of people you will ever meet. Discuss with them a topic they do not like, and they will have you banned within minutes. Want to swear or show your friends pictures of more mature things? Ban. Want to through tacks at people? Ban. That's not even the half of it, but I'll save you the details.
I recommend that you avoid going into Second Life. If a friend asks you to join them, slap them across the face and tell them never to say those words again.
Beyond the people, The graphics are deplorable. Sure, you can make it look like the best damn thing ever, but you better have a super gaming computer. One of the reasons SL is so resource demanding is because of the Prim. Basic objects you put together to create more complex objects. Looking at an object, your eyes only see some of the polygons, but your computer has to render the rest that you can't see, thus forcing your computer to do more work then it has to. They did recently introduce (recently as in they were too dumb to do this in the beginning) Mesh uploading, where you create a 3d object outside of SL, then upload the .dae (not .obj or anything else unfortunately) file, thus allowing you to save polygons.... if you did it right.
While we're on software, get this: Second Life is running on programing that is 10 years old. They've only gone in and added or subtracted stuff. That old code needs a total rewrite. I'm sure it was fine back in 2000 and 2005, but now it so full of "fixes" that it has become the problem.
Oh, and that's another thing: Every time Linden Labs fixes something (linden labs being the creators and maintainers) they break something else. Just a year ago, they introduced a new "Viewer." (viewers are the programs that you download so you can log onto the grid and interact with people). This Viewer 2 was totally different from Viewer 1, thus forcing the old user base to re-adjust. It was aimed at helping newcomers get used to SL faster. I do not remember taking a survey about what a new viewer should have. I suppose something like this was in the agreement statement: "We have the right to force you to use whatever we want you to use." Doesn't sound very user generated, now does it? They basically said, "we care bout our old residents, but we want more money.. I mean residents."
Most of the Residents in SL use a Third Party Viewer instead of the viewers supplied by LL, showing how unreliable LL technology is. Now mind you, the Third Party Viewers are based off of the viewer supplied by LL, but they feature security fixes, better features, and better integration.
But the problem remains: SL is full of harmful people, you need the best damn computer to run it (and a really nice network), and the caretakers are doing a lousy job.