Dash Express is a unique product that is changing the value proposition of connected GPS navigation in the already-crowded GPS market. Unlike other navigators that download traffic incident or flow information from road sensors installed throughout the United States, Dash is building its own network of connected drivers. Each Dash Express driver becomes a live traffic probe, anonymously sending traffic information back to Dash so it can be relayed to other drivers in the area. Essentially Dash Express is a connected mobile computer, able to receive software updates, traffic updates, and other enhancements seamlessly over-the-air.

Historical traffic data fills in the gaps for roads without live data, creating a remarkably accurate picture of current road conditions. During my testing, I was highly impressed with the quality of Dash's traffic information, even in rural areas where I was very likely the only Dash driver for miles. Dash is also the first GPS device to report surface road traffic conditions as well as highways.

There's simply no denying that Dash has developed the most accurate and complete traffic information available on any GPS today. That's the good news. The bad news is that Dash Express is so singularly focused on traffic that it falls short in many of the more basic areas. Dash's menu system can be confusing, and the device exhibits almost none of the refinement and polish of a Garmin, Magellan, or TomTom GPS.

The map screen does a good job displaying traffic conditions, but it can be difficult to see upcoming turn maneuvers or the route you're supposed to follow. Panning and zooming the map is very slow, as is route calculation. I also lamented the frustrating situation of seeing red traffic conditions ahead, but having no way to exclude a specific road or segment from the route.

Then there's the size issue: Dash Express is bulkier and heavier than any other GPS around. Granted, Dash has Wi-Fi and GPRS connectivity, but so does the iPhone, and at a fraction of the size and weight. I'm not sure why Dash didn't put the Wi-Fi and GPRS receivers into the (already bulky) windshield mount instead of the GPS, but the sheer size and weight of Dash Express may turn some consumers off.

Priced at $299, Dash's monthly subscription service, required for traffic updates and Internet-connected search, costs $13 for month-to-month service, $10.99 per month for a 1-year contract, or $9.99 per month for a 2-year commitment. The device ships with three months of service included for free. Dash Express can still be used without an active subscription, but you'll lose traffic updates and connected Yahoo search. Without an active connection, Dash Express has a paltry 1 million Points of Interest onboard. Most other GPS devices have between 4 and 8 million installed.

Commuters who must regularly tackle traffic conditions and are primarily looking for a "traffic avoidance" device will find much to like about Dash Express. Dash's TruTraffic is the most accurate and complete traffic service available to date, and it actually works. As a standalone GPS, Dash Express still feels rough around the edges, and a work in progress. I must admit that after several weeks of testing Dash Express, I was happy to return to the relative elegance of my Garmin nuvi. Unless traffic avoidance is your primary objective, you might want to wait until Dash smoothes out the kinks before buying Dash Express.