i have one of these and i'd have to say that the review at infosyncworld.com is a little dodgy. they are correct about the baudrate/port thing, that should be fixed, but the joystick being concave is actually a good thing, because then you can use the stylus to operate the joystick (handy when you're using the stylus for other things, e.g. writing on the screen).
as for the inaccuracy, i guess this depends on the location as well as the car. some areas have better maps than others, and some cars offer better visibility than others. i use mine in a hyundai getz and i don't even have trouble navigating through the city.
and the software can be upgraded too, i think the reviewer is a little harsh when he deducts so many marks for that. as always, when buying devices like this you should consult multiple reviews, and not be turned off (or on) by one or two odd ones.
to simplify: i have a navman pin and it's a brilliant product that hasn't once let me down and is an absolute joy to use. | 
Navman PiN Review 
Linear Mode
