Built-in navigation systems is in most case real ( s**t ), for small country no coverage and map update 1 time in year cost 200€ - 500 € every year
If you buy PND you pay 1 time 300€ and you can update your maps 4x in one year.
So if you calculate you will see that PND is still cheaper.

Free GPS on smartphone is not free becouse you pay for downloaded data and also if you buy app for smartphone this is only for play or for walk and not for real navigation.

If you use Navigation every day the number one choice is still PND.

So here is example:

Built-in navigation systems = you pay it when you buy car and also every year for new map 200-500€.

Smartphone = about 500$ and up and then you must also buy app and map's or pay for downloaded data and app is locked to your phone.
So if you buy new phone you must pay again for app.

PND = One time cost 300$ and you can update maps lifetime.

So let me know when you calculate what device is cheaper

p.s.
1 thing not to buy in 2014 is Built-in navigation system