This stuff is actually better than Google Maps if we're talking about finding your way around Russian cities. Tap on any building and the app will give you the full list of organisations located there: from cafes and drug stores to the offices of big and small companies. You can also run a quick search for whatever you're looking for on the map and find out what's the most convenient route towards it. Overall it's a useful Russian Google Maps twin stuffed with more accurate and thorough information.
For Moscow it's a real must have. The app is a life-savior especially for those who're new in town and may find it difficult to orient themselves in the monstrously vast Moscow subway line system. The app is also available in English which makes it a lot easier for foreigners to learn the names of the stations and to adapt to their cyrillic analogues. It also contains the metro schemes of other Russian and a couple of Ukrainian and Belorussian cities, so if you feel like going exploring St. Petersburg, Minsk or Kiev during the weekend, this app will be just as usefull for you out there.
The app that helps you to navigate through Moscow using it's on-ground public transport. It contains a map with all the bus, tram and trolley stops tagged on it. By tapping on each of them you can see the full list of transport routes passing through it. The app also shows the most accurate time in which the vehicle shows up at the stop you're currently waiting at. Be sure that this is one more cause when you better trust this app than your favorite Google Maps.