Unlike many disaster movies that milk a certain disaster for all it is worth (Twister being a classic example), Dante's Peak really has only one major disaster. The first hour or so of the movie is spent building up a human interest relationship between its two main characters, volcanologist Harry Dalton (Pierce Brosnan) and the Mayor of Dante's Peak, Rachel Wando (Linda Hamilton).
I think it is a good idea to build in some emotional depth to the characters in a disaster movie, as this leads to greater tension and empathy for the victims when the disaster strikes. However, in the case of an action flick like Dante's Peak it backfires miserably. The audiences come wanting to see explosions and Dante's Peak waits too long to deliver. By this time, we're as tired of waiting for something to something to happen as Dalton is of Wando's coffee.
I think with some editing (say 15 minutes to a half-hour) this could've been a far better movie. There are some interesting scenes in the movie, however, which may make it worth renting someday. The opening visuals and the music is decidedly gothic, which I think puts volcanic eruptions in the right perspective. There is an eerie scene where Dalton, Wando, her children and her mother-in-law, are trying to get away from lava and end up in a boat in an acid-filled river singing Row, Row, Row Your Boat. Depending on the kind of person you are, you will find this hilarious or disturbing. There are some semi-gross scenes involving burnt bodies as well.
The scientific basis for the movie appears to be fairly sound. A few events that required some significant suspension of disbelief included Dalton's vehicle going over a bed of hot lava and come out relatively unscathed and Dalton outrunning a pyroclastic flow of ash and gas.
While Brosnan and Hamilton do adequate jobs as actors, the supporting cast do a terrible job generally. Almost everyone except for Brosnan and Hamilton are window dressing. As fellow reviewer James Berardinelli pointed out, Dalton's colleagues look like refugees from Twister's ragged band of storm hunters. If that doesn't turn you off, Dante's Peak is worth the matinee fare.