It's just using both the GPS system and the GLONASS system (the Russian satellites) to improve accuracy. So now, instead of driving down the wrong side of the street (on the map) you'll be on the right side.
30 feet is accurate enough for me. If my nav app tells me to turn right and I'm still 25 feet from the intersection, I don't make a turn into a store window. I have the phone high enough on the dash that I can glance at it when I make a turn to see the name of the next street I'm turning on, so even if it doesn't tell me to turn when I get there, I know not to wait until I passed it to make the turn.
But it's something Qualcom can use as an advertising point.
And trust me, moving to a new city gives your nav app a real workout. I still don't know 50% of this city at all and 90% of it well, so unless I'm going somewhere I go all the time, the nav app is running. (My wife has a Magellan in her car that uses only the US satellites, and it's just as accurate as any nav app on a phone.)