Foursquare: Should I join?

One of the new social networking ideas is something called "Foursquare".  Basically, when you go out to places, you "tag" where you are and you can also leave "tips" on the place's site for what somebody else may want to check out ("Try the new Jumbo Burger.  It's divine").  You can leave "shouts" that announce that you're there and invite others to join you, or just tell people what's going on there.  It's also kind of a game, as people can rise in status and become "mayor" of a certain place if they've visited that place the most often in a two-month time period.  Restaurants, coffee houses and the like actually have given discounts to Foursquare participants who are frequent visitors to their establishments, especially if they become "mayor."  When you announce that you are at a place, anybody on your friends list will see it immediately, and can head there themselves if they want to meet you.

I'm just wondering whether I should take part in this.

Mashable has an article titled "6 Tips for Getting the Most ouf of Foursquare", and one of the tips is to choose your friends on the network wisely.  This isn't like Facebook, where you will never interact with these people other than online.  You are telling people where you are at any certain time, so you should make sure that you at least know the people who you "friend" on the network.  On the other hand, as the article also says:

"Using Foursquare by yourself is like playing tennis alone. The fun lasts about three seconds. In geekier terms, it’s like having zero followers and following no people on Twitter. To get value from Foursquare, your friends need to be in on the action, too. Then you can use the app to meet up, share tips, and find stuff to do with when you’re bored, among other things."

So if I don't have many (any?  if you're out there, tell me!) friends on Foursquare, what would be the point?

What I'm looking for is advice on how to use it and whether it's right for me.  If none of my friends are on the network, I would be playing that tennis game alone and it would get awfully boring, though I do believe any tips that you post are accessible by anybody who goes to that place (am I right?).

Convince me that I should join this network that looks like a fun concept but may be kind of useless for me.  Volunteer to be my friend if I join (does that sound needy?).  And if I actually know you, then maybe I'll accept.

I'm just looking for other people's experiences.  We'll see what happens, and I'll talk more about it if I do end up joining.