LinkedIn might have a lot of similarities to Facebook when it comes to the search engine, messaging, even the timeline, but if you're trying to get yourself out there - LinkedIn is a good place for it. You're likely going to find groups that cater to your specific area, people who have the same job as you that you can connect with, and so much more.
I've connected with many people on LinkedIn as I'm an Open Networker and have found it to be quite enjoyable. I've posted in groups, shared links, told people about myself and heard some stories of how other people operate, and more. I've even made a few friends on there.
Now with that said be careful of who you talk too. Lots of people I've noticed will send you a sales pitch, and will be focused on trying to make a commission off of you instead of getting to know more about you. Some people will even try to scam you with fake job ads - promising you lucrative salaries, all expenses paid for, but sadly those aren't going to happen. Not unless you got an official message from a reputable company saying that. Does the term "419 scammer" ring a bell? They're scattered throughout LinkedIn. Luckily people can detect them more and more, but they can still slip through the cracks.
Overall this gets 4/5. A good place to showcase your skills, talking a bit about yourself, and opens you up to a plethora of opportunities. Even the simplest of things like networking can be great since you're opening yourself up to new people and new ideas. The new layout of the site stunk quite a lot though, but most people seem to have adjusted to that.