I was one of the early adopters of Foursquare, back when they didn't actually monitor if you were at the location or not so you could check in with your non-smart phone and still achieve points, etc.
But the main question I've always had is about their business model. To be completely honest, I eventually stopped using Foursquare because it wasn't improving my life at all. Some establishments have perks for being the Mayor, but with the rampant "cheating" and forcing someone to visit and location time after time in succession, it became more of a hindrance than a help.
I still don't see where their business model is entirely, but I don't feel they have much of a future, unless people enjoy checking in to places for the coming future.