This is a horrible movie but it can be horribly fun if you watch it with friends, and you just make jokes and laugh about how stupid the movie is, which I'm pretty sure is exactly what the intention of the film's producers was.
Basically this movie is about a huge earthquake which somehow opens up a sinkhole in the earth but it also simultaneously somehow awakens a colony of ancient and incredibly dangerous, deadly poisonous and aggressive spiders.
That really sums it up. The story doesn't really have any surprises and all the shocks and scares you will see coming a mile away. But there are a lot of fun moments and so bad they're funny death scenes. Pretty much every possible way you could picture spiders killing someone is covered in this movie.