This depends on the data available on Foursquare and in Open Street Map. Generally, urban areas have more Foursquare venues. If you are in the area that you want to use BlindSquare in, you can go to http://foursquare.com and check which places Foursquare does know in your area. You can also check how well your area is mapped by going to http://www.openstreetmap.org.
If you are blind or visually impaired, you may need sighted assistance to read the map on Open Street Map. You can also e-mail a street address of the area you want to use BlindSquare in to firstname.lastname@example.org or by using our contact form, so we can run a simulation to see if BlindSquare will work for you.