Once you've started the directions, you'll zoom in on your current location, represented with a blue circle and an arrow in it. The current direction will be given with a large road sign-style dialog box at the top, along with an icon indicating what action you need to take, if any. Siri will speak any directions aloud; if you're playing music or other audio, it will fade out slightly while Siri tells you what to do, then fade back in.

As you continue, your location will update and you'll be prompted with subsequent directions; just like in earlier versions of Maps, a blue line will show you the route you're taking.

At any time, you can tap the screen to get an ETA, along with distance and time. Two buttons let you either end the directions or return to the overview mode, and you can pinch the map to zoom out and back in a small amount. Other than that, you can't do anything else in the Maps app while directions are being given. However, you can use other apps at the same time: In that case, you'll see a blue-green bar at the top that says "Tap to return to Navigation"; whenever a turn is imminent, a banner alert will appear with the information about the upcoming direction and Siri will speak the instruction aloud.

If you lock your phone while in navigation mode, Siri will continue to give directions and you'll be able to see your current location and any other upcoming direction information on the lock screen.

There are a lot of nice touches to navigation mode. For example, I like the floating signs that identify nearby streets, and the fact that the streets you're going to actually turn onto are marked in blue rather than in green. The instructions to make turns and such are generally large and easy to read, which is good, since you don't want to spend time squinting at tiny text while you're driving.