... What is a good score? An excellent score? average?
As Privateer0 points out, the "final score" really doesn't have much meaning other than comparing various playings of the same
game. That can be one player replaying a game in different styles for his own intellectual amusement, or a number of different players playing the same game in a virtual competition.
Look in some detail at the Scenario Editor / User Scenarios / Competitions
board at this site, and you quickly will see threads about some of the competitions that go on here.
One of the things you should note about how/why the "final score" has little relative meaning across all games is the way the elements of the score change based on the set-up of the game. That is, the elements of the score are not constant for all games -- so how could there be a good, better, best level for any or all games?