I use CityMapper in London an I'm a huge fan of it. Some of the features I love the most are:

- Foursquare results when searching for a destination

- Saving a trip plan to access it without Internet connection (handy when changing lines underground)

- Get me home and Get me work shortcut buttons on homepage

- Underground line statuses

- Rain safe travel options

- Taxi prices for the chosen travel

- Very user friendly design