The New International Version [NIV] (copyright 1973, 1978, 1984, the International Bible Society) is the by far the leading Bible purchased today by English-speaking Christians. Since 1987 it has outsold the KJV and now represents approximately 40% of the Bibles sold in the US. (The KJV represents about 20% of the Bibles sold today.) As described in its Preface,

The New International Version is a completely new translation of the Holy Bible made by over a hundred scholars working directly from the best available Hebrew, Aramaic and Greek texts... The fact that participants from the United States, Great Britain, Canada, Australia and New Zealand worked together gave the project its international scope. That they were from many demoninations -- including Anglican, Assemblies of God, Baptist, Brethren, Christian Reformed, Church of Christ, Evangelical Free, Lutheran, Mennonite, Methodist, Nazarene, Presbyterian, Wesleyan and other churches-helped to safeguard the translation from sectarian bias... From the beginning of the project, the Committee on Bible Translation held to certain goals for the New International Version: that it would be an accurate translation and one that would have clarity and literary quality and so prove suitable for public and private reading, teaching, preaching, memorizing and liturgical use. The Committee also sought to preserve some measure of continuity with the long tradition of translating Scriptures into English...

According to Phillip W. Comfort, Philip W. (The Complete Guide to Bible Versions, Wheaton, Illinois: Tyndale House Publishers, Inc., 1991):

The translators of the New International Version sought to make a version that was midway between a literal rendering (as in the New American Standard Bible) and a free paraphrase (as in The Living Bible). Their goal was to convey in English the thought of the original writers.

For some significant verses, the NIV maintains wording more similar to the KJV's wording than does the NRSV. For instance the Hebrew word adam was translated in the KJV as follows: man Gen 1:26,27, Gen 2:5-25, 3:12-24, 5:1 (and elsewhere); Adam: Gen 2:19 (and always wherever else the name Adam appears in the Old Testament); person Num 31:28 (and elsewhere). In Genesis 1:26,27, along with the KJV, NAB, NASB, NJB, NKJV, the NIV also translates the Hebrew word adam as "man;" whereas, the REB and TEV translate adam "human beings;" the NRSV translates adam as "humankind" (NRSV), and the CEV translates adam as "humans." browse http://www.bibletexts.com/terms/heb-adam.htm to read a commentary on the use of the Hebrew word adam.

For some other verses the NIV translation reflects a fundamentalist slant that often does not take into account the nuances of the Greek text. For some examples of this, please refer to the BibleTexts textual commentaries on Joh 1:1 and Joh 1:18 at http://www.bibletexts.com/verses/v-joh.htm. Viewing its translation and interpretation as representing fundamentalism, several very prominent, internationally respected (non-fundamentalist) biblical authorities with whom I have spoken about the NIV give the NIV a very poor ratings. It has been said that regardless of it great popularity, it is not a serious translation.

Summary: The NIV is quite compatible with wording in the KJV; generally has a much more accurate Hebrew, Aramaic, and Greek textual foundation than the KJV; however, it does have a decidedly fundamentalist slant in some of its translation and sometimes in its selection of the Greek readings, but the NIV does remain the most-sold English language Bible version in print today.