Cinemazement has a video review of the TomTom Go 510 GPS unit. Actually, the video is more of a demonstration of the 510 than a review, but it's interesting nonetheless.
Their thoughts: bluetooth cellphone calling is mediocre but useful, driving directions are sometimes off, and the touch sensitive screen has easy to navigate menus. The unit doesn't require a computer to set it up at first, which is a nice change from some of the older competitor's models that has you installing maps before it's usable.
Tomtom Go 510 GPS [Cinemazement]