I like it a lot, too. You do with it what you like ... collect witty sayings or pictures of cats or pictures of your favorite cars or ideas on things to make from wooden pallets or gardening ideas and how-tos or DIY cleaning solutions or recipes (for food or drinks) or how to crochet or knit or pictures of places you want to travel or beautiful or fascinating buildings. You define it for yourself, you can "pin" things from elsewhere on the site or anywhere on the internet or upload your own photographs.
I avoided signing up through Facebook, as well, although I don't remember exactly how I did that. I can spend hours on there in one week ... and then not go there for weeks at a time. It can be very inspirational and/or very soothing to use Pinterest, I think. I used to clip things from magazines and newspapers all the time, and then ended up in envelopes and boxes and file folders. Now they all end up on Pinterest, and I don't have to worry about the clutter.