Switching to the Garmin has been a very positive change. The routes are basically always correct. If not, and I choose a different direction, it quickly recalculates to the route I have chosen, rather than trying to force me back to it's chosen route for the next 100 miles.This right here is why I wanted to throw the RM out the window. The way Garmin looks up addresses is far superior, as a minor mis-format in the address doesn't require using GPS coordinates.
Mind you, as I've mentioned before, they are little more than toys and upcoming corner finders to me, so the routing is something I do on my own anyways. I never have the voice on for that reason, they're always SO disapproving of my choice of routing! Athough as Mike noted, the RM hangs on to it's initial route entirely too long before adjusting to your new route.
And yes, it is just a tool/toy, but a useful one.