It's kinda like Facebook or Google+, but it's supposed to keep you interacting with actual friends, not 5 bazillion pseudo-friends/acquaintances/people-you-don't-really-care-that-much-about. I had read some good things about it online, so I tried out the iOS app. Now I'm sorry that I did. They've been caught uploading everyone's address book. Without the user's knowledge or permission. They've admitted their practice and defended it.
Path uploads your address book
So I've deleted the app and recommend that you not install it.