"When a meteorite from outer space hits a young California woman named Susan Murphy and turns her into a giant monster, she is taken to a secret government compound where she meets a ragtag group of monsters also rounded up over the years. As a last resort, under the guidance of General W.R. Monger, on a desperate order from The President, the motley crew of Monsters is called into action to combat the aliens and save the world from imminent destruction!"
(Above taken from here).
This was a fantastic movie, with plenty of action and amusing scenes right from the start. I'd say it's most definately worth a watch!