Footage from the Witcher 3 panel won't be up for some time, but thanks to live tweets from the event we've got some idea what happened in there:
Technical difficulties mean there's been no audio from the gameplay footage, but Geralt's voice actor, Doug Cockle, is on hand to provide context.
The gameplay featured the use of fast travel which is available outside of cities, and showed the ability to visit any location on the map. Best of all, in case you missed it in previous gameplay trailers, jumping confirmed:
Geralt can jump btw just in case you were wondering #Witcher3 #SDCC #SDCC2014 #thebgb— Better Gaming Bureau (@TheBGBCom) July 24, 2014
"Will the game still have random difficulty spikes?" -- "We worked really hard to have this nice curve (this time)" @witchergame #SDCC— Nerd Appropriate (@NerdAppropriate) July 24, 2014
In other words, nothing new here.