Back To The Future 3 was good as well (It has a 78% on RT).
Back on topic, there a chance it may be bad because 4 is a very number for movies such as
SuperMan 4: Bad
Batman & Robin: Very Bad
Alien: Resurrection: Bad
Police Academy 4: Citizens on Patrol: It was ok but still bad
Jaws 4: Very Bad
A Nightmare on Elm Street 4: Bad but still Allright
Rocky 4: Sucked!
Saw IV: Bad