The microphone is the big new feature. We also adjusted the colours and layout. These updates were released on the 19th of November 2014, for both PBPhonics 1 to 3 and PBPhonics 1 to 7.
(If you are wondering what PBPhonics is, you can find a description on the PBPhonics page.)
Because iOS tries to protect you from inadvertent privacy breaches, apps that use your microphone must first ask permission. So, the first time you launch PBPhonics after the 2.0 update, you will see this: