I'm planning on buying a new GPS unit. I had a Garmin 660 a few years ago, but it was stolen out of our car. Ironically, we bought it because we were moving to a new city, and it was stolen from our car after we'd only been in our new location for about a week.
The units I'm contemplating are the TomTom 540, the TomTom 740, Garmin 1390, Garmin 1490, Garmin 765, or Garmin 855. I was leaning towards the TomTom 540, because of the 5" screen and because it's a really good price- but then I read online that the TomTom 540 and 740 don't do in route route changes very quickly (i.e. when you miss an exit, it'll automatically update your route), and our old Garmin did that really well. My wife wants to be able to use it to get around the city when her sister visits this summer, and she doesn't know it very well- so having it be able to update the route on the fly, and do so quickly, seems like a good idea.