I get asked to compare POTC to GNR fairly often. It's really difficult to compare the two because they are very different games that play differently (like all JJPs.)
There are some "signatures" you'll notice though:
- The through-the-pops EB shot
- Building a stack of simultaneous multiballs with visual indication on the LCD (4 booster multiballs in this case vs the sixes on POTC)
- A few callout easter egg references to POTC
- The character concept for adding buffs to gameplay is moved to patches, which you can ignore if you like or leverage to great advantage
The upper playfield loop feels good and is repeatable, but not in the way POTC's is. POTC keeps building speed each time and gets harder to keep looping.
GNR is best described as a two-stage game, stage one being building up your song boosters and stage two performing the song.