It also works globally as long as there are some users there, while Yelp only supports a few countries.
I was in Zagreb, Croatia for the very first time last year and wanted to eat dinner somewhere other than my hotel. I tried Google Maps and it was worthless. I pulled out Foursquare and found a restaurant a few streets away that turned out to be incredible! (So much so that when I went back a few months later I went back to the same place instead of exploring.)
And now that I mention it, same thing happened to me in Tallinn, Estonia, too. Found a great brew-pub-ish restaurant that I would have never found on my own. And again, went back a few months later on my next trip.
I kind of assumed from this experience that Foursquare has better adoption in some areas of the world, but I'm not sure.
You want to look at the websites for newspapers and the like. Rio Show, Veja Rio, etc.
I mean, do I really have to give a full report in order for me to be satisfied with the product?
(For size reference, I live in Baltimore, MD.)
Edit: I'll add, too, that "check ins" that get posted socially seem to be viewed increasingly as self-indulgent "look at me and my lovely life" signals.
There was a time that such posts, along with "pics of my delicious dinner at trendy restaurant", etc., were regular and acceptable. That time is quickly passing, I think.
The analogy is talking about how much money you have, or how cultural you are, etc. This isn't really polite and most people secretly roll their eyes in response to it. It appears either calculated or in incognizantly bad taste.
This is just an anecdotal observation, of course. But these kinds of things have basically disappeared from my feed, which might just be an effect of an aging list of friends rather than a broader usage pattern. I suspect it's a generally emerging standard of social media etiquette though.