It's a great piece of Software that includes everything from a simple bulit-in tuner to display scales to sync the backing track (as MP3) along with the guitar tab. It can import any mayor guitar tablature file format I know and enables you do learn much quicker than with any other guitar app that I've tried.
BUT it is no longer free. From version 4.x you pay. The actual price is ardound 40U$ (incl. discount):