At Christmas Sony offered a major update to the tablet, not over wi-fi but via PC. This requires using their 'PC Companion' program to download and then transferring to the tablet using the USB cable that doubles as the charging connection. I guess this is to avoid "Oh noes my internets just died!" problems.
Anyway all went well, Android went from 4.2 to 4.3 and several Sony bits changed. The most obvious change is that the camera interface is a lot easier to use.