The Sony Ericsson Xperia J comes with a GPS receiver, which took about two minutes to get satellite lock upon a cold start. You can use the A-GPS functionality to get near instantaneous locks. Alternatively, network positioning will do if you only need a rough idea of your location.
Google Maps is a standard part of the Android package and we've covered it many times before. It offers voice-guided navigation in certain countries and falls back to a list of instructions elsewhere.
3D buildings are shown for some of the bigger cities and you can use two-finger camera tilt and rotate to get a better view of the area.
Google Maps uses vector maps, which are very data efficient. The latest version has an easy to use interface for caching maps - you just choose "Make available offline from the menu" and pan/zoom around until the desired area is in view (there's an indicator showing how much storage caching that area will take). You can later view cached areas and delete ones you no longer need.
Note that there's a limit to the size of the area you can cache - you can't just make all of Europe available offline, not even a whole country. We managed to fit New York and some surrounding area before Maps told us the area is too big. Also, there's no address search in the cached maps and you can only cache map data in supported regions of the world.
You can plan routes, search for nearby POI and go into the always cool Street View. The app will reroute you if you get off course, even without a data connection.
The Sony Xperia J runs ICS, so it has access to most of the latest apps. The Store is organized in a few scrollable tabs - categories, featured, top paid, top free, top grossing, top new paid, top new free and trending. The in-app section is untouched though and it's very informative - a description, latest changes, number of downloads and comments with rating. There are usually several screenshots of the app in action, and oftentimes a demo video as well.
There are all kinds of apps in the Google Play Store and the most important ones are covered (file managers, navigation apps, document readers etc.), so if you wish you could do something more with your phone, odds are it's in the app store.