• It's android OS 2.0 only for now. And will be available when devices like that ship. (Google demo'd the app to us on a Droid, FWIW.) Other platform support will be announced "by carriers and phone makers" when they're ready, but Google implied they are working closely with Apple now on it.
• Addresses are input by both text and voice (using the same tech as in the iPhone's Google mobile app). But the app can take things like business names and restaurant types as well as soft queries like "that museum that has the king tut exhibit" and return a list of suggested locations
• The traffic data, as on Google Maps, is driven by multiple sources. Typically, this means data from local road authority services like the Bay Area's Caltrans department's highway cameras, but also data from cellphones using Google Maps.
• It's free, and there are no ads. There's nothing like it in the App store that's less than $50 bucks a year.
• Maps cache along your intended route, so even if your connection dies along the way the route will still show you what you need to see, and voice synthesis of street names still works, too.
• Like most cloud map services, you'll never need to update your map data.
• It has satellite view, which is super cool for context on the street, but also, it has streetview. Streetview images come up, overlayed with arrows, when you're supposed to turn. Or at your final destination. Since streetview images have metadata on direction faced and position, Google Maps Navigation intelligently draws the arrows where you're supposed to go. Sort of.
• Traffic icon is simple — green, yellow and red according to flow of traffic, with time to arrival numbers next to the symbol. If you click on the traffic icon, the map zooms out to show congestion points along your route.
• There's no multiple route selection to help you plan a day's drive of many locations. But you can search for locations (gas, eateries) along your route, and those results will show up on the map as long as they're within a radius that moves long your path.
• You can go to a navigation point by simply holding onto a point on the map.
• You can bookmark locations as icons on your Android phone's home page.
• If Google sells this in the app store for zero dollars, those millions of bucks Apple makes off of GPS app sales will likely disappear. It's not for us to worry about until there's no more GPS competition except Google, and we're dependent on their pace of progress, but no competition is a bad thing. And it's a little strange that Google's search money is going to pay for a free map app that is competitive with stuff that costs $100 a year from full time GPS makers like TomTom. Unfair is the word that comes to mind. But I can't say I don't want this App.
• The data on the map, like traffic, satellite view and points of interest, are called layers. Google said it would be easy for them to add more layer, so its ostensibly possible to add things like Google Latitude support, and other neat tricks. Maybe they'll open up an API for it.
• There's a landscape and portrait mode, as well as a big-icon UI for dashboard usage.
A visual tour of Google Maps Navigation:
