Hell, I think the first FF movie had more intensity than this one. And anyone who says Sm2 was less intense than 1 would get slapped silly. The train scene took super hero movie intensity to a whole new level, and it really did look like the end of Spider-Man when giant sandman was beating him, I felt every blow.
I'm not quite sure how intense a PG movie can get, but I can tell you they lost a big part of the audience with that PG rating from lack of intensity. They dropped the ball.
The scene that really stands out for me was when the FF was trying to stop that ride from falling. I think that was the most intense moment. Now if they had done something like that times 2 for the final battle, that would've been great.
A scene that would've really sold the movie is an early fight with the Silver Surfer, with all members giving everything they had, and Surfer still tossing them around. Finally, leaving them all unconscious.
Also, ginat galactus trying to suck the earth dry with the FF all over him.
Again, there wasn't a feeling of urgency, even when Galatacloud was coming. Spider-Man could've replaced the whole fantastic four easily in this movie. And I shouldn't be saying that. Put them in situations that only a group of superheroes can escape from when they work together.
I want an intense Fantastic Four movie, they might have gained some kiddie viewings with the PG rating, but they lost alot of the male older demographic with that. Give the public an intense FF movie and the public will make that movie a huge success.