The restrictions seem to work well, especially with the recent software update, but the map data itself seems to be lacking somewhat.
For example...
I used it to get me to an address on an Industrial Park in Biggleswade successfully, but when setting next target address, it reported a bad start location. I had moved approx 200 yds from 'the beaten track' so to speak and it couldnt see my gps location on the mapping. I have to tell it to plan a route from a known location (last target) to the next.