I got Guitar Hero – Greatest Hits over the weekend and going through the tutorials, found that with the new slider-guitars you can also “tap-strum”:
The slider bar can take the place of the normal strum bar (you can tap-strum). Instead of strumming you hold the fret-buttons and tap the slider. You can use it to create different “wah” effects, use it for hammer-ons/pull-offs and hitting a crapload of notes in a row without strumming. It does seem that the GHWT-guitar suffers from build-issues, as star power can now only be activated with force.