TrustedReviews have looked at the Mio Digiwalker A501 GPS PDA Phone

Mio's A501 is a reasonable stab at melding both smartphone and sat-nav. It has a touch-screen, which mobile phones with sat-nav bolted on generally don't, and it's also smaller than most PDA phones with GPS. If you truly don't want to be bogged down with yet another gizmo when popping out and about, it's worth considering for these features alone - especially as the driving guidance is so good. Overall, though, there are just too many other flaws for a wholehearted recommendation. The screen's too reflective, the software slightly laggy and the phone itself isn't the prettiest or the most fully featured. And if that lot doesn't put you off maybe the £334 price tag will.

Mio Digiwalker A501 GPS PDA Phone Review