Metro 2033 is missing from this thread. It might not be a generational leap, but it's a HUGE improvement on PC and one of the best looking games for what it does. It might not have large areas and little loading, but it looks amazing overall.
Like I said earlier though, it's hard to say a generational leap unless huge developers spend a significant amount of time on the PC version without worrying about the consoles first. Hardware wise, it's a generation ahead, but it's not in terms of most games due to the studios' focus elsewhere. But take a look at a game like Shogun 2: Total War, and the size and scale of that game is definitely unrivaled. It's just insane and it's new expansion is even better.
Like I said earlier though, it's hard to say a generational leap unless huge developers spend a significant amount of time on the PC version without worrying about the consoles first. Hardware wise, it's a generation ahead, but it's not in terms of most games due to the studios' focus elsewhere. But take a look at a game like Shogun 2: Total War, and the size and scale of that game is definitely unrivaled. It's just insane and it's new expansion is even better.