Out of date, DONT buy! – CityTransit - Official NYC Subway Maps Review

This last update to this app is over a year old. I loved it the first 2 years that I used it, but changes in MTA and a lack of updating have caused it to be an unreliable source for getting you around town. Plus, it doesn't offer any information about buses in any other borough other than Manhattan (which coincidentally is easy to navigate by bus without a map because it's just a grid). Until they begin to update regularly, just use google maps, which will even give you scheduled subway and bus times.
Review by greengobstopper on CityTransit - Official NYC Subway Maps.