I bought the HTC One a couple of months ago and thought that feature was great, just navigate to anywhere, zoom out as far as you want and click on save map offline, turn off wifi and 4g data and pull up the GPS app and it uses the stored map. Most everyone I know has iphones and they were like Wow, that's nice, turn by turn voice offline nav.
Offline maps has never seemed to work reliably on my Nexus 7. I save a map offline, drive a few miles, start up the Nexus and it says it can't load the map! I think it worked on ONE occasion (and it was brilliantly useful), but then stopped again. As far as I can see, Google keep intermittently messing it up / fixing it with each update.