I use Google Maps as my "go-to" for usual navigation in the car and on foot. However, I have been badly bitten on return journeys when Google got me to a place but couldn't get me back again on another day as there was no 3G coverage and the cached map was gone.

It's for this reason I always have Here maps loaded on my phone, together with the relevant map for any country/area I need to drive in. I'm 99% confident of data coverage walking around a city.

I've also adopted my daughter's old Nokia as a "Holiday Phone" - downloading maps as needed for city trips and popping a SIM card if needed. Don't care if this gets lost, dropped or stolen. It's not as attractive as an more modern phone and it's small and light.

I do also have a Garmin GPS unit that I take walking - only for occasional geo-caching trips with the kids and as a "I'm lost - help" backup.

Not sure if I'm the only one, but I use directions off Google Maps but then have the actual map open to Waze (to see construction/speed cameras etc)

Yes, HERE maps is my backup as well.

I have the TomTom App installed on my iPhone to solve this problem. It works entirely off line (except for the real-time traffic subscription). Note that it does take more than 1GB of space due to the large offline maps.

I use the TomTom and Navigon apps for use on my phones to avoid/minimize use of online data. Works well enough for me in North America and Europe.

While the apps are memory space hogs -- TomTom more than Navigon (as the latter let's me pair down by map selection) -- they are as effective as even the dedicated GPS devices the major car rental companies provide. At least when it comes to getting directions.

Why do people like HERE more than Google?

It's reliable when offline

Most of the descriptions of it were as a backup, and the full offline routing support in Google Maps is very new.

pros: it has superior functionality offline
cons: seems to destroy battery on an android phone
day to day, when online, i still prefer google for total integration

How many maps does HERE download?

As few or as many as you want or your storage allows

you select on a country by country basis
for countries which is more data dense, such as germany, you would be able to select individual states e.g. bavaria, baden-wurttemberg

After downloading maps, do they update ever or would you need to manually update if there are changes?

all other like apps notify you when offline maps need updating (usually full replacement, not incremental upgrade).... i suppose HERE should do the same