It only has one use, you can go as far back or as far forward as you want. For the sake of discussion, I'm going to say that you HAVE to use this machine and you must go at least 50 years forward or 50 years back.
Do you go forward or backward in time?
Do you want to live in a simpler and more traditional time?
Do you want to see what advances we've made and how much society has globally integrated?
If I had to choose, I'd say forward because I'd love to see how far we've come, and the thought of the unknown excites me. Part of me also yearns for a simpler and more traditional time, but the urge to go forward overpowers that.