It also suggests faster routes by walking to another station rather than getting on at the one you may be by.
E.g say you are outside Bow Road station and want to go to Canary Wharf. That's a journey on the district line to West Ham, change for the jubilee and then to Canary Wharf. 16 minutes and then ballache of changing line.
Citymapper will say, don't be a plonker. Walk two minutes to Bow Church DLR and go straight there. 9 minutes.
Simple examples but there are even more than that which significantly differ.
Ace app. I use it every day even after living in London for over seven years (I have a lot of meetings).
Convinced by all the bigging up of Cityplanner, I downloaded the App.
Living in London, I KNOW the best subway lines to use to get anywhere, where to switch, etc., granted I'm not an habitual bus user, you can spend half an hour on those just going from Centre Point to Marble Arch along Oxford Street.
I put in some test trips, and it came up trumps every time, granted, I wasn't interested in walking times and stuff, but it gave the best methods of A to B.
Then today, my wife has to meet a friend at Kensington Olympia, we live in Rotherhithe, SE London, so we both knew that the best way was Bermondsey Station to Green Park on the Jubilee Line, Green Park to Earls Court on the Piccadilly Line, then Earls Court to Olympia on the District Line.
Just for kicks, she punched it in on CityMapper, it suggested Jubilee, Bermondsey to Bond Street, then Central Line, Bond Street to Shepherds Bush, then walk to Overground Line station, one stop to Kensington Olympia!
So although Citymapper is undoubtedly good, it's not infallible, I'll keep the App, but use it warily.