THE GOOD:Graphics, Sounds, Has a story, Gameplay is fast paced and easy
THE BAD:
Don't expect a flight sim game with details like flatspins, realistic payloads, and that sort of thing. The Ace series takes jets, puts players in them, gives them 50 missiles, and tells you to blow *bleepity bleep, bleepy bleep* up. 
SUMMARY:
Ace Combat 4 is an arcade flight game. Quick handling, quick speeding, quick breaking, in the blink of an eye. Seek and destroy, run out of ammo? Return to base, re-arm/fuel, and head back out and kick some more enemy *bleepity bleep*! The graphics are enough to put Gran Turismo to shame. Not too much though, but better.
Great sound effects, a clean flight engine (at least its decent for a non realistic flier game), and a great...