It's got an extra voice mode, much like the Banno Driver, it's got Chase's quotes in chronological order. Also there's the extra Triple Tune effect.
Triple Tune can just be done by tapping the button while any of the Chaser Cores are inserted, which is a nice touch for people that don't have all three of them (The Execution/Full Break is still there by holding and releasing it), it retains all the functionality of the original Break Gunner (including the show-inaccurate "Drive System" insertion for the Type Change Cars instead of "Tune: Drive System"), and still keeps those added features. Quite possibly the best toy in the Drive line.
Also, the Rhino Super Viral Core is a reskin of the Tridoron Key and that is hilarious to me since they both end up making repainted new head retools of the Mashin Chaser suit.
Eventually, there will be something here.... Eventually.