From his 3rd edition Old Testament Exegesis (WJK, 2001) – (p. 103):
2.1 Translation theory
A good translation not only renders the words of the original into their best English equivalents, it also reflects the style, the spirit, and even the impact of the original whenever possible. You are the best judge of what consitutes a faithful translation. Your familiarity with the passage in the original, and with the audience for whom you write or preach, allows you to choose your words to maximize the accuracy of the translation. Remember that accuracy does not require wooden literalism. The words of different languages do not correspond to one another on a one-on-one basis. It is the concepts that must correspond. Your translation should leave the same impression with you when you read it as does the original. A translation that meets this criterion can be considered faithful to the original.
Along these lines I tend to have a preference for median translations (e.g., TNIV) mainly because my personal opinion is that these translations best show the tension between sometimes having a literal translation and somtimes having a more dynamic translation all depending on the sentence or phrase being translated. I am fine with a literal (supposed word for word) translation if it, as Stuart argues, “maximizes the accuracy of the translation.” But it is more the dynamic translations that “leave the same impression with you when you read it as does the original.” So I like the blend and I see it the best in a translation such as the TNIV.
See also, Nick’s post: Hilary of Poitiers on Literal Translation.