Meister said:
What do you recommend for North America and Europe?
GPS manufacturers license mapping data from either Navteq or Tele Atlas. Navteq's maps are generally reviewed as being more accurate and up to date (but the license is more expensive for the GPS manufacturer). Navteq is also based in the US, so you probably want a device that uses Navteq maps if you are mostly in the US.
The converse is true of Tele Atlas, based in Europe, but you should check for specific city coverage.
Garmin licenses mostly Navteq, TomTom licenses mostly Tele Atlas (though there are some exceptions, depends on the device), so, if you are mostly in North America, you'll probably be happier with a Garmin, and if you are mostly in Europe, you'll probably be happier with a TomTom.
TomTom's interface is a little nicer, but Garmin's is fine (esp if you move up to a Garmin Nuvi).
Meister said:
How does it work for adding/buying maps?
Depends on the device, not all devices can use all maps.
Meister said:
What about updating maps in 5 years?
Garmin has updates, some cost money:
http://www8.garmin.com/unlock/update.jsp
TomToms would be similar.
You should note though that GPS devices and chipsets are undergoing rapid evolution right now... in 5 years, any GPS you buy now will probably be sadly obsolete.
For instance, there are new GPS chipsets that lock on satellites faster, or will be able to do dead-reckoning using accelerometers (more accurate positioning), 5hz operation (most current GPSs are 1Hz) etc.
But don't let that stop you, GPS is pretty useful if you spend a significant amount of time driving to new addresses. It's always nice to see side-streets to take shortcuts, or just to help home in on an address.
If you have a Blackberry like an 8700 or newer, you can just get a Bluetooth GPS dongle like a Holux 236 or Globalsat 338 for about $100, and use Blackberry Maps (free). Works fine. Uses data though (it downloads your current map location dynamically) so hopefully your office is paying for your data plan! It works great, and it's surprisingly useful to have a GPS in your pocket all the time.
(Older blackberries with bluetooth are supposed to work, but I heard the processors are too slow)