Navigon MobileNavigator

More than any other GPS app, Navigon MobileNavigator for iPhone feels and works like a traditional GPS device, reviews say. It offers all of the features experts say are important: on-board maps (so navigation won't conk out when your cell signal does), spoken street names (so you'll hear, "Turn left on Maple Street in 100 feet," rather than just, "Turn left in 100 feet") and (for an additional $25) traffic alerts. Nice extras include lane guidance (MobileNavigator tells you which lane to be in at major highway interchanges) and reality view. Navigon seizes upon the advantages of iPhone, too: It works in both portrait and landscape format, with full iPod control while you navigate. No other GPS app on the market, including the rival TomTom for iPhone (*Est. $100), can do it all, reviews say.

But Navigon is also one of the priciest apps you can buy, and it only works on the iPhone. Other highly rated apps are compatible with more phones. ALK CoPilot Live (*Est. $35) offers most of Navigon's features at a fraction of the price, but it doesn't always navigate as accurately. TeleNav GPS Navigator/AT&T Navigator (*Est. $10 per month) downloads maps on the fly via cell signal, which takes up less phone memory than on-board maps (but can be less reliable), and its database of 10 million points of interest is far larger than Navigon's 2 million.

Plenty of excellent review sources have tested Navigon MobileNavigator, but the most recent reviews are the most valuable, as Navigon added key features (traffic alerts and spoken street names) to the app in late 2009. ConsumerReports.org is the only source we found that tests the new traffic alerts. Other sources, such as The Dallas Morning News, Macworld and About.com, include the new text-to-speech feature in their testing. User reviews at the Apple App Store are short and not always of high quality, but they are up to date.