Picking up a new van in March, was going to add the sat nav to the van, but the sales chap ( large Nissan dealership ) told me the maps are out of date before you drive away, so to stick with my Tomtom !!
Now that Google Maps lets you save maps offline, meaning that it works great even when in non 3G areas, I'll probably continue to use that. At least with Google you know its always pretty much up to date.
Its just annoying that a new vehicle comes with such out of date sat nav data.