One of the new features in https://www.trueachievements.com/Rock-Band-4-Temp/achie....htm
is the freestyle solo
and they are the subject of a new video from Harmonix, where some Rock Band
fans - presumably the ones that play guitar in game - gave their opinion on the feature.
You'll be able to get your freestyle on when Rock Band 4
launches on Xbox One on October 6th.