At first I was a bit nasty on Sygic support before finding out how this currently works (sorry guys :-) ), but my version of the program on Android has a two-stage update process. It first downloads an (relatively small - usually a few MB large) update from the Google Play store and then, after you run the application again, proceeds to download an (much larger) additional package in the application itself. It will refuse to navigate until this is complete.
I had problem where I had the app on auto-update, and joined a Wifi-cafe network while I was abroad. It updated via the google play store and when I wanted to use the program to navigate a few hours later, it refused to do so (until I downloaded the second stage update as well). As abroad this would've cost me a lot of money (more then I paid for the app itself, and I bought the whole world package), I was not impressed.
I would therefore appreciate if the app would update itself as a whole over Google play, to prevent from situations such as these. Until then, I switched auto-update off and update manually at home.