From the 2011 Christianity Today article:
The Council on Biblical Manhood and Womanhood, one of the leading critics of the TNIV, promised a full review of the updated NIV after it goes to print. In November , when online text of the updated NIV became available, the group released a statement saying it could not recommend the new NIV Bible because of "over 3,600 gender-related problems" that were previously in its critique of the TNIV.Read it all.
In other initial reviews, some evangelicals praised the clarity of the new edition while others were still unconvinced that the gender-related problems of the TNIV were resolved. Statistics compiled by Christian web techies Robert Slowley and John Dryer show that 31 per cent of the TNIV is retained in the updated NIV.
Many reviewers thus far are not fans of the mixing of gender-neutral singulars and plurals like "that person" and "they" in the new text.
You can read the Council's report here (PDF file).
I also recommend this article: "From the NRSV to the New NIV: Why Gender-Neutral Language Represents an Enforced Agenda Rather than a Natural Evolution," in the Journal of Biblical Manhood and Womanhood. It is a PDF file. You'll have to scroll down to pages 27-30.