Do you use Foursquare?

I recently (read: Today) signed up for a social networking site that is gaining more and more popularity; Foursquare. I first heard about Foursquare from a news segment that sparked my interest in the whole thing. The best way I could find to describe Foursquare is what I found from a news article online: [Foursquare in a nutshell is] a cross between a friend-finder, a social city-guide and a game that rewards you for doing interesting things. At first I found the concept kinda cool sounding. You gain points and badges for visiting a place so many times or what not. You can also leave tips or comments about the places for other users to see if they visit that location and it all sounded pretty cool to me. Obviously this is more useful in a big city so I was somewhat skeptical about downloading the app on my phone but was pleasantly surprised to find tons of locations in my area. You also have the option to add locations which gives you more points as well. One thought that crossed my mind after was that people could break into your house or take advantage of the fact that they know where you are all the time but Foursquare has thought of a way to deal with that. There is an option to update your location without updating your friends and you appear as "off the grid" so privacy really shouldn't be an issue for this site.
The only real downside I've found so far is most of my friends have never even heard of Foursquare, however more and more people have been predicting Foursquare becoming the next big social networking site so I'm hoping you all jump on the bandwagon or at least give it a look for yourself. And if you do decide it sounds interesting you should add me!