You've seen it all before.
The main monster movie formula hasn't changed since the 1950s: The petevil technology of the time (radiation, pollution, germ warfare,genetic engineering) in conjunction with the pet villain of the time(mad scientists, the CIA, right wing militias, evil industrialists)turn some natural creature into a dangerous mutated version of itself.Fighting it is made harder by clueless citizenry, corrupt politicians,and head-in-the-sand bureaucrats. Frequently the good guys are aided bya guilt-wracked insider. In the end, some sound or scent is often usedto lure the creatures into one place where they can be destroyed.
The variables are filled, in this entry, by pollution, evilindustrialists, vampire bats, and music. Instead of an explosion, theyare killed by steam. We don't see much of the insider, who is usedmainly to throw the audience off as to which character is a crook.
This movie isn't as silly or heavy-handed as many movies using thisformula, plus the acting is better, but the fact remains that you'veseen it dozens of times before. (Although the choices of eviltechnology and favorite villain always result in some reviewer gushingthat it was "ripped from the headlines.")