Yeah, it is better to get the recommended vitamins & minerals from food, but personally, I am too lazy to calculate whether or not the food I eat every day is sufficient, so I take one as a back up. I get the generic ones, so they don't really cost that much.

There are some vitamins that you can have too much of and experience ill effects, but a once-daily multivitamin shouldn't have enough of anything in it to cause problems unless you've got other issues going on where you're either not correctly processing or storing too much of something.