It allows you to rotate and ‘slice through’ a brain scan in 2D and 3D, and click on specific areas to get their names. It’s straightforward to use, and is available for Linux, Mac OSX and Windows.
Some of the most important buttons are in the bottom right hand corner of the main window but are poorly labelled. They determine whether you are selecting the lobes, sulci (the ‘trenches’) or gyri (the ‘ridges’) when asking for on-screen labels.
If the surface of the brain looks slightly odd in the BrainTutor software, it’s because BrainVoyager tends to accentuate the sulci during visualisation. This is presumably to enable a better view of the brain activation when it occurs on the surface.