First off--HUGE improvement to the UI. It's a little bit like Facebook timelines; every post is smooth and uncluttered and in chronological order.
There is an automatic update feature that will create a post whenever you visit a new neighborhood. You can create posts for photos, friends, location, music, text, and sleep/wake times. These posts can be shared with Facebook, Twitter, Tumblr and Foursquare (in addition to your Path friends.) If you're feeling shy, you can also create private posts.
Much like the Facebook app for iOS, swiping left or right produces menus. To the left is different options, to the right is the list of friends (you can have up to 150 of them.)
So far I've been using the app primarily to check into places and post to Facebook/Twitter. I like having one app to cover posting to three social networks. I could do the same with HootSuite, but it wasn't as pretty.
The photo post functionality includes some real-time Instagram-like filters. In-app purchases will get you more filters.
So far, I like it. It's simple, it looks damn good, and it works. If you add a lot of Path friends, it becomes another social network, but if you mainly use it to post to your other social networks, it is a time-saver that looks better than any other app I've tried.
Have you tried Path yet? What do you think of it?