map updates have never been free...it's because the GIS (Geographic Information Systems) companies (tomtom, garmin, nokia, telenav) charge a very hefty fee for this data. It is for this reason that Google creating their own dataset and essentially giving it away (so they can track us and advertise) was so revolutionary, especially considering that a virtually free product has become the defacto gold standard.
a disadvantage phone based nav has is that it's connection dependent (both cellular and GPS signal, unless you took the time to pre-cache an area) and as such can fail in tunnels, urban canyons (tall buildings) and areas where mobile connectivity is questionable....these don't affect cars because they can then resort to dead reckoning as backup using the cars compass and odometer in these situations until the car re-establishes the GPS link
as previously mentioned, a disadvantage to car nav is the static nature of the data set stored and it becoming more out of date as time passes
I use both so have no worries