Dave Brunn, in his book One Bible,Many Versions says:
"Every version translates thought for thought rather than word for word in many contexts." (p.189)
"Every version steps away from the original form in order to be grammatically correct in English." (p.189)
In The Story of the New International Version :
"As for the NIV...flexible use of concordance and equivalence, but with a minimum of literalism,paraphrase,or outright dynamic equivalence. In other words,the NIV stands on middle ground --by no means the easiest position to occupy."
Rod Decker :
"I think it's fair to conclude that in terms of translation philosophy the ESV is closer to the NIV than to the NASB."