The Bible is the word of god, written by man, this should always be taken into consideration, regardless of your beliefs. This knowledge is essential when reading the text, and should lead you to the path that it is to your own discretion where you believe that the bible is word for word accurate in advocating Gods beliefs or values.
Religion itself is a personal matter, therefore the way you interpret the book should be a personal matter, as with many things, discussing with others and review of your own ideas will lead you to greater understanding on the subject. It should be for no one else but your own judgment to decide what you should take literally and what should be seen as a metaphorical analogy. Beliefs are the only thing that is truly your own. To jump in and say to somebody "you shouldn't have taken that part so literally" might seem like madness when it questions something you yourself have taken into deep consideration already and achieved a certain understanding on the matter, whether it may be favouring certain parts of a religious text or merely learning values from a common story.
Of course, certain people favour certain parts of religious texts to have a clear and concise meaning, where as other people will look over it to be seen as a descriptive example, this is the problem that exists from interpreting text that has been written by man, there are many contradictions within the bible, and there have been many revisions that have taken place over the long course of time, usually based on rulers and leaders in power. This doesn't mean the person who takes it literally is wrong, It just means that they feel much more comforted by the fact that they themselves do not have to question what is and what is not true, this requires an enormous amount of faith and in a way, they should be commended and respected for it. However this can in some cases fuel fundamentalism, and fanaticism. With such a rich and diverse text it is extremely easy to take one part of it and focus on it too much.
If you take a belief method of your own and apply it to such a question, you're undoubtedly going to be bias in your reason. I myself am agnostic, and therefore the fact that I do not believe there is enough evidence in the bible to convince me that a god is real, I do not believe any of it should be taken literally, since I find the foundation of the belief itself pointless, and to some extent I think that it should be dealt with using a degree of common sense. Common sense cannot be applied to faith.
BTW, metaphors are descriptive imagery in which you apply the description to an object/whatever as it is itself that object, similes are the other method of description where you liken an object to something.
ps. Sorry for the bad grammar