Ja! I think map data quality is VERY region dependent.
Honestly, I really like the look of the Navteq maps versus the Teleatlas maps. My brother has a Garmin Nuvi200 and we've traveled with both that and my Tomtom ONE v2. I guess they are both the base models and it was interesting to see how they compare.
We drove around to some of the new developments and neighborhoods and both devices were complete (I'm running the NE regional map 7.10(?)). No missing streets on either. So in this limited trial, it was a tie. Same with the general quality of the display and the audio, in both our opinions.
The Nuvi was considerably slower in acquiring satellites. Also, I was still getting five satellites in my basement on the Tomtom, whereas he was losing all satellites any time he brought the Nuvi into the house.
In terms of OEM features, The Nuvi has the calculator, world time and the image viewer, which, honestly, if you think about it is sort of silly and superfluous. Even my brother agreed - he had never used any of these features. He didn't even know it had the picture viewer. He doesn't even have an SD card either. I can't help but think that these features are like having a bowling ball that also brushes your teeth.
Generally, in terms of navigational aides, my Tomtom has more view settings and features, but his Garmin's POI searching was faster and more intuitive. Overall, the GUI on the Garmin just seemed slicker, more refined. In terms of ease of use, I think the Garmin has an edge. It was much easier for a new user like me to quickly plan a trip and find a specific restaurant on his Garmin. My brother had to peck and hunt a bit more to do the same simple tasks on the Tomtom. But honestly, the amount of modification I've done to mine (ie. car icons using ttheaven, offroad navigator, suntimer, custom start/shutdown pics, voices, media player) was a big factor. My brother isn't one to tweak technology - he'll just open the package and use it as intended. So I have no idea how robust the 3rd party and user / community content is for Garmins.
Honestly, I'm delighted with my Tomtom and he's delighted with his Garmin. To each his own, eh?
Now, my mother's Tomtom ONE v3, on the other hand?!?! I CAN'T STAND IT!!! Can't get any of the tweaks to run on it...