I'd disagree and would judge the game individually.
What makes you think I'm not judging it individually?
FO2 is strongly derivative of FO1. That's a fact. It obviously doesn't mean it's a bad game as many people rank it quite highly. Some people, for reasons I don't understand, even like it more than FO1. It didn't offer much that was new though, and it was also a rushed product when it was released.
Sure, you might play it without ever playing FO1, but then you would be missing out on a superior experience.