This was the second movie at the drive-in double feature (the first one was Journey to the Center of the Earth, which is just below this one, because I write these in the reverse order from the way you read them), and it was much worse. It's surprising how different two pulpy Brendan Fraser movies can be, really.
Basically, I disliked almost everything in this movie. The only thing I approved of was the way the characters seemed to have remembered the previous movies. A lot of times, you have a scene where people say "What? The mummy has come to life? Inconceivable! That's completely impossible, even though I've seen it happen several times before!" That happened fairly frequently in Buffy the Vampire Slayer, where people were always saying things like "Oh, sure that guy cast a love spell on the student body. A likely story!" even though supernatural things were happening all the time. Mummy 3 avoids that. As soon as the Dragon Emperor starts coming to life, everyone is snapping into action and firing guns and so on. Good for them!
Unfortunately, things break down pretty much immediately so we have a pointless chase and the always-welcome sight of archaeologists destroying priceless artifacts. And there's a comic relief yak that's only in their for three stupid throwaway jokes.
I should mention that even bad movies are better at the drive-in, because it's fun to shout things at the screen and know that no one can hear you. Except the other people in your car, and they're probably shouting things too.