TomTom started it and now Mitac is joining the fray, taking advantage of more screen real estate to add social media functionality into a PND. Makes a lot of sense to me. A car navigation unit is still generally better at navigation than a mobile, at least where the mobile is not running a true car navigation application with maps etc.
Most people aren’t aware of the enormous detail contained in portable navigation devices. This extends to things like turn restrictions and one way streets, up to date speed zones, road class, paved roads vs dirt roads and much more. Of course these devices are only as good as the quality of the map and service providers. Don’t assume because the brand has a good name, or the software works really well, that they have the best maps available for your country. Do your homework before you buy.