The Google Maps app is a good reason to buy an Android phone. No other Google Maps version offers 3D maps, free turn-by-turn navigation, voice-guided navigation for walking directions or offline caching. No other Google Maps app is updated so frequently with cool features.
For instance, Google Maps 5.7 for Android combined Google Maps Navigation with transit directions and introduced an innovative feature called Transit Navigation. "Now, GPS turn-by-turn (or in this case, stop-by-stop) navigation is available for public transit directions in 400+ cities around the globe with Transit Navigation. Transit Navigation uses GPS to determine your current location along your route and alerts you when it's time to get off or make a transfer. This is particularly helpful if you're in a city where you don't speak the language and can't read the route maps or understand the announcements."
It's a really useful feature and the coverage is continually expanding. I suspect that Google Maps will find other clever ways to use notifications: location-based reminders, recommendation alerts ("notify me when I'm near an Italian restaurant"), social alerts ("notify me when I'm near a restaurant recommended by my friends").
Google Maps for Android also added a navigation icon next to the driving and walking directions, a photo viewer for Google Places pages and icons that categorize search suggestions.
Probably the most useful new feature is buried inside Google Maps Labs: on-demand maps caching. Tap the "menu" button, select "More" and then "Labs". Enable "download map area", long press on the map around the area you want save, tap on the bubble and select "Download map area". Google Maps will download the map area within 10 miles (16.09 kilometers) of the selected location and outline it. This feature only saves map tiles, so you won't be able to see satellite imagery, Street View images or get driving directions while offline.
The 10 miles limit can't be changed, but at least you can manage your downloaded maps. Use the "Cache settings" option from the menu and select "Downloaded map areas". You can rename map areas, delete them and quickly visualize them.