The first and most pertinent question about Paul W.S. Anderson's Pompeii is: "Why is Milla Jovovich not in this?" At least half the upside of seeing any Anderson movie is the probability that his hot, badass wife will appear in it. But aside from this truly egregious omission, Pompeii is a totally passable popcorn flick.
The story starts with the premise of a real historical event: the eruption of Mount Vesuvius in the year A.D. 79, which so impressively flooded the Italian city of Pompeii with red-hot lava and ash that it preserved many artifacts (everything from pottery to people) for archaeologists to find hundreds of years later. Against this backdrop, you get the familiar plot of a gladiator named Milo (Kit Harington), sold into slavery when his tribe was sacked by the Romans, and Cassia (Emily Browning), the woman he falls in love with. Cassia is a princess, or whatever the equivalent to a princess was in the era of Roman city-states, and it just so happens that a ridiculously evil senator named Corvus (Kiefer Sutherland) already has dibs on her -- besides, Milo is just a lowly but proud slave.
But do all of those class differences really matter when everyone's about to die? Milo and his rival-turned-bestie Atticus (Adewale Akinnuoye-Agbaje) are determined to find out. So what you basically have is Gladiator (togas and swords, pair of black and white gladiator BFFs fight for their freedom, revenge sought for slaughtered families) crossed with Titanic (impending disaster, poor boy loves rich girl, pointlessly evil romantic rival burns calories being mean during cataclysmic panic). Of course, both of those movies won Oscars for Best Picture, and you can bet Pompeii doesn't aim quite as high. It's adequate entertainment though, even if it would be better with Milla Jovovich.