the "great extra features" are launch control, anti-lag, flat shifting, Map sensor instead of AFM (though it will take an AFM if you want), built in boost control with the addition of a solenoid, onboard data logging, dual fuel and ignition maps with real time change over (you wire in a switch to do so)(E85/other fuel tune and your standard 98 tune for example).
There are probably other things i have missed but they are the main ones that come to mind.