Just before Christmas, we cashed in "reward points" on a credit card we were about to cancel. Among the items ordered were two Global Positioning System (GPS) navigation units.
Not knowing any better, nor investing any significant amount of time on comparative analysis before placing the order, I decided to get one TomTom (the XL 340-S) and one Garmin (the nüvi 255). Though the TomTom retails for nearly $100 more than the Garmin, both were roughly the same amount of "reward points". Had I known then what I know now, I would have gotten two TomToms -- it's a far superior unit in nearly every way.
Both the TomTom and the Garmin offer 2D (top-down map) and 3D (rolling terrain) views. Both units have similar mounting equipment, and both have the same USB interface as the Motorola Blackberry (i.e., we have lots of cables and power cords to accommodate these units). Both have "Favorites" options along with user-selected icons for common destinations, a top-menu selection when going "Home" (but, curiously, not one for going to work), and both offer voice prompts for upcoming maneuvers -- though the TomTom has a greater variety of voices to choose from.
For the economically-minded-to-the-last-cent, the Garmin has a "Trip Total" feature that tracks total mileage, time stopped, and fuel cost based on user-entered data such as average price per gallon and fuel economy of your car. I suspect the fee-based monthly update service also includes a "cheap gas finder" feature, but we did not invest in any such recurring costs.
The TomTom, due to its wider 4.3" screen, shows much more data on the basic display -- including ETA to destination, slack time (if you entered a desired arrival time), as well as a countdown timer showing time remaining to destination. It also has a much stronger antenna, quickly picking up signal indoors where the Garmin won't.
The TomTom provides advance notice of upcoming maneuvers, including the turn after the next if there is less than a quarter-mile between turns. It also gives lane-specific information when driving on Interstates, showing which lanes will continue to your destination, and which will divert you to Abilene.
Both provide a digital (on-screen) keyboard for data entry, but the Garmin's is awkwardly given in alphabetical order -- while the TomTom gives a QWERTY keyboard-style interface.
Also, the Garmin will go into a reboot cycle when the source power is turned on (e.g., when starting your car) -- regardless of whether or not the system was powered up. The TomTom, when off, stays off if you turn on your car. When using a different power cable (e.g., my Blackberry's USB cable plugged into a USB-to-12V-cigarette-lighter-adapter), the Garmin enters a 55-second long boot cycle -- a major inconvenience if power is interrupted in any way while in transit.
The TomTom comes with a basic map pre-loaded, but without many "Points of Interest" available. The full map update is a 2GB (yes, GIGAbyte -- or 2,000 Megabyte) download -- so be sure you have high-speed Internet and a couple hours to let it churn. The Garmin also has a 2GB download required for its map update, but the basic load out of the box is ready for navigation.
Nothing "ugly" observed so far on the TomTom. But the Garmin (even with a map update) is still lacking many local destinations -- even some more than a year old. (Case in point: entering "Buffalo Wild Wings" on my Garmin showed the nearest destination more than 40 miles away in Denver, even though there is one just five miles from our house.)
That's where the TomTom really trumps the Garmin. The TomTom menu screens (of which there are just two, thanks to the larger screen, compared to three for the Garmin) include a "Map Corrections" option -- and the ability to download map corrections made by others. Given the fees charged by these companies for map updates (you get one bundled when you purchase, and the TomTom offers unlimited downloads during the first 60 days), this feature alone is worth choosing the TomTom over the Garmin.
Hands down, the TomTom is a far superior device. My theory is that Garmin, the first name in GPS units, has taken the same lackadaisical tact that Palm did in the smart-phone market: resting on its laurels, content with its massive market share, it has been overtaken by the upstart Dutch company that went public in 2005 and whose revenues have grown more than 200-fold since 2002.