Of the original 7, it's always been Back on Track that's the least memorable to me. That can be partly attributed to being flanked on either side by some of the most iconic and well-constructed levels in the game's history, but it's mostly the fault of the level failing to make the most of the song's most distinct and important moments - the whole level just feels kind of indifferent to its own difficulty and scale, and the introduction of jump pads was never particularly impressive itself. There's still some interesting weight to the ship and ending cube, at least.