The NIV has always been an agenda-driven translation, and the agenda is evangelical. The introduction to the NIV Study Bible says it quite clearly:
All [scholars involved] confess the authority of the Bible as God's infallible word to humanity... Doctrinally, the NIV Study Bible reflects traditional evangelical theology.Which is at least up-front. Beloved of evangelical Christians, the 1984 NIV has become the translation of choice for many, and perhaps most, and the officially sanctioned version of several denominations (including GCI). When the TNIV was launched in 2001 however, it was not received with a chorus of hallelujahs. Conservative evangelicals, knickers tightly knotted, were selectively appalled at the updated language, and especially the move to be more gender inclusive. Plans to replace the NIV with it were quickly withdrawn.
That said, the TNIV seems a far improved translation. Gender inclusive language is the way we speak today, whether the old NIV curmudgeons like it or not. The two versions were however still shackled together. The introduction to the NIV Study Bible (2008) begins: "The New International Version of the Bible (NIV) is unsurpassed in accuracy, clarity and literary grace." Be that as it may, the introduction to the TNIV Study Bible (2006) begins: "Today's New International Version of the Bible is unsurpassed in accuracy, clarity and literary grace." Uh? Okay... maybe someone can explain how that could be...
And of course, identical words to those first quoted above are also used to outline the excellencies of the TNIV's evangelical credentials. The new edition will be more of the same, but a more cautious foray into the twenty-first century than TNIV attempted. It's intended to replace both the existing NIV and TNIV, so get your copies while stocks last. But it must now compete with the ESV, another agenda-driven translation with even greater pretensions, despite being little more than a doctored rehash of the old 1950s RSV. Sadly, the really worthwhile English versions sell far fewer copies because they don't pander to biblicist insecurities.
The 2011 NIV has already hit the bookshelves, though I haven't seen one in my corner of the Antipodes yet. I suspect, though, that it too will be "unsurpassed in accuracy, clarity and literary grace."