I fired up both the TomTom ONE, which uses Tele Atlas maps, and the Garmin StreetPilot c550, which uses NAVTEQ maps, and entered 112 Henry Sanford Road, Bridgewater CT as my starting address, and 100 Main Street, Westport MA as my destination address. The units produced very different results to the same destination:

TomTom ONE (Tele Atlas)	Garmin c550 (NAVTEQ)
	Right on CURTIS RD Right on Chritian St Left on Sarah Sanford Rd W Right on Sarah Sanford Rd E Right on Hut Hill Rd Right on South St Left on Purchase Brook Rd Right on Spruce Brook Rd
	Right on Britain Rd Right onto I-84 E to Waterbury Exit 27 right to I-691 E to Meriden / Middletown Exit 11 left to I-91 N to Hartford / Springfield
TomTom Estimated Drive Time: 3 hrs 31 minutes	Garmin Estimated Drive Time: 3 hours 2 minutes

I know this area very well, and although both units will get you to the same destination, the TomTom ONE will take a route that is almost 30 minutes (14%) longer. Not only that, in the above example, the Tele Atlas powered TomTom ONE is trying to route us along the most congested main road in the area, so we'll likely also run into traffic, making the trip even longer. NO question about it: NAVTEQ chose a much faster route in this example.

Just for a sanity check, let's look at what Yahoo! Maps gives us for the same starting and destination addresses:

1. Start at 112 HENRY SANFORD RD, BRIDGEWATER going toward PLANZ LN - go 0.6 mi
2. Turn on CURTIS RD - go 0.2 mi
3. Bear on CHRISTIAN ST - go 0.8 mi
4. Turn on SARAH SANFORD RD - go 0.7 mi
5. Turn on HUT HILL RD - go 1.7 mi
6. HUT HILL RD becomes MINOR BRIDGE RD - go 1.3 mi
7. Turn on SOUTH ST - go 0.7 mi
8. SOUTH ST becomes BROWN BROOK RD - go 1.1 mi
9. Turn on PURCHASE BROOK RD - go 0.7 mi
10. Turn on SPRUCE BROOK RD - go 1.9 mi
11. Turn on S BRITAIN RD[CT-172] - go 2.1 mi
12. Continue to follow CT-172 - go 0.3 mi
13. Turn onto I-84 EAST toward WATERBURY - go 20.2 mi
14. Take exit #27 onto I-691 EAST toward MIDDLETOWN/MERIDEN - go 8.7 mi
15. Take exit #11 onto I-91 NORTH toward SPRINGFIELD/HARTFORD - go 6.7 mi
(rest of the trip truncated since all three sources were the same from this point on)

Total Drive Time on Yahoo! Maps: 3 Hours 3 Minutes.

Yahoo! Maps (also powered by NAVTEQ) routes us the exact same way as the Garmin StreetPilot, and had the same estimated drive time.

OK - you've been warned. Live in the US? Look for NAVTEQ on your next GPS!