If I understand Danito correctly: the characters in GF radiated more physical danger and fear, as individuals. The situations were more direct, more personal and in some respects, more violent. The dangers were far more subtle in II and III, but no less dangerous. The villains were even more villainous, but much less physically menacing.
Hm, the most violent scene was probably the Atlantic City massacre. FFC followed the rule, that with every sequel, the brutality has to increase. Problem: It doesn't affect me that much.
For example: The Senator Geary story is in some ways a parallel to the Woltz story, and it's handled in a similar way. Difference: Dead horse vs. dead girl. But the dead horse scene was more scary, wasn't it? Not from a rational side. But it was a completely unexpected shock. In GF2 we see Tom walking through the brothel, the prostitutes were trembling. What do we get? A naked senator.
The villains were perhaps less physically menacing, but first of all cinematographically.
