Of all the many musical genres, I think metal is by far the most misunderstood. I will be the first to admit that metal isn't for everybody, and that to some degree, is intentional. Metal will forever be a fringe genre, occasionally finding a brief spotlight of popularity with some of the more radio friendly bands, but the majority of its diversity remains unknown. Diversity in metal is one of the things that most non-metal listeners don't appreciate. There are as many or more sub-genres within metal as there are sub-genres within the amorphous blob of folk/bluegrass/pop/americana.
One of the most commonly heard fallacies about metal is that it's 'angry' music. While it's true some metal can be called angry, I would say the majority of metal isn't. Metal topics run the gamut of emotions just like any other genre, just maybe a little more intensely felt. Metal genres often embrace the darker parts of humanity, choosing to contemplate rather than ignore.
In the end metal is just like every other music genre; it can be complex or simple, dark and scary or light and joyful. So whether you love it or hate it, next time you here metal blasting out of someones car window, try to hear it with ears unclouded by misconceptions.
Here's a couple of examples of different kinds of metal that I've been really into lately.