For me, it’s not a game-changer, but the reason is not the app; it’s the transit-friendly locations of my apartment and office. I’m lucky; I live in a neighborhood with a good bus system. My front door is within five minutes of three bus routes that take me straight to the office; all of them come pretty frequently at peak commute hours.
I’m never tempted to drive, since the bus ride takes about the same amount of time and let’s me catch up on reading. Plus, compared to the hundreds a month I’d spend on gas and parking, the bus is a steal. It’s the perqs of living in a walkable neighborhood close to the urban core and crisscrossed with transit lines that make my commute a breeze.
I absolutely agree that transit access (and especially frequent service) is far more important than any tool, but I also think the picture is bigger than how fast a person can get to work. Hess acknowledges that OneBusAway and similar tools would likely be more useful for someone who depended on one bus with infrequent service. Let me add that they are also extremely useful for people who use the bus for purposes other than commuting.
I don’t use phone tools nearly as much I could–both because my phone’s not the greatest and because I often find looking up the information to be as tedious as waiting–but on days when I’m clothes shopping with two kids and need to know when to put on hats and coats and head out into the cold and rain, or when I’m at a party on a (low-service) weekend night and would prefer chatting with friends to a lonely wait at a deserted stop, they make all the difference.