TomTom Mobile (downside you need a phone it supports) but an excellent solution, can use speed camera database (no need for a B2), poi overlays for Mc d's etc...
I use it with an spv c500 screen is big enough and volume levels fine
You take it with you when you get out of the vehicle (well it's your phone!!) - Recently used it in Spain and was spot on (required Spanish map)
Also on the plus side can use it when out walking, biking, or even in a mates car (gps unit size of a swan vesta box)
Link