Many say the changes of the NIV don't make any difference, but I came across the following discussion.
"As you no doubt know, the critical text uses Nestle-Aland 27th ed with variant readings. Nestle-Aland relies primarily on, guess which two manuscripts? Sinaiticus and Vaticanus! What is TRULY amazing is that Westcott and Hort are now considered to be comparatively accurate! More so than the Received Text (TR)
As for the NIV, it does massacre the text in some important areas, regardless of which manuscripts are relied on. One example is Hebrews 9, where the NIV changes 'holy place' to 'Most Holy Place.' Also, Colossians 2,'sabbaths' to 'a Sabbath day.' Etc."
"Hebrews 9 says that Christ entered the 'greater and more perfect tabernacle . . .' and that He entered the Holy Place. v. 12 says that Christ entered the Holy Place, ta hagia, not the Most Holy Place, hagia haggiwn. The NIV, along with Desmond Ford, have attempted to change that. In vv. 24ff, it says He sacrificed Himself. But your best clue is found in what you yourself have said. His stated work was 'to make intercession for us.' That is the distinctive ministry of the courtyard and the Holy Place. The work in the Most Holy Place was a work of judgment....Heb. 9 specifies that Christ entered ta hagia, the holy place, as opposed to hagia haggiwn.
Christ's ministry as our intercessor occurs in the holy place, within the veil. That is what began shortly after his ascension. "
and there are more changes that affect doctrine and the changes also affect the New King James version, here is a good article to go over...
"Let us look at the two Bible versions most in use by Protestantism––the NIV and the NKJV, and compare them with the Authorized King James Bible to see if they are in harmony with these divine, irrevocable criteria established by God Himself.
THE SABBATH
KING JAMES BIBLE – “But the seventh day is THE Sabbath of the Lord Thy God…” Exodus 20:10. This is speaking of a definite and particular day of the week, which we know refers to Saturday, the seventh day of the week on the calendar.
NIV VERSION – “But the seventh day is A Sabbath to the Lord your God...” Exodus 20:10. By substituting the definite “the” for an indefinite “a,” this takes the emphasis of any particular day and leaves one free to choose any day of the week as “a” Sabbath day––a subtle attack by Satan on God’s holy Sabbath day.
THE DEVIL
KING JAMES BIBLE – “By the multitude of thy merchandise they have filled the midst of thee with violence, and thou hast sinned: therefore I will cast thee as profane out of the mountain of God: and I WILL DESTROY THEE, O covering cherub, from the midst of the stones of fire...Thou hast defiled thy sanctuaries by the multitude of thine iniquities, by the iniquity of thy traffic: therefore WILL I BRING FORTH A FIRE from the midst of thee, IT SHALL DEVOUR THEE, and I WILL BRING THEE TO ASHES UPON THE EARTH in the sight of all them that behold thee. All they that know thee among the people SHALL BE ASTONISHED at thee: THOU SHALT BE A TERROR AND NEVER SHALT THOU BE ANY MORE.” Ezekiel 28:16, 18,19. Here, the King James Bible clearly speaks of a FUTURE judgment to fall upon Satan.
NIV VERSION – “Through your widespread trade you were filled with violence, and you sinned. So I drove you in disgrace from the mount of God, and I expelled you, O guardian cherub, from among the fiery stones. [verse stops here]..By your many sins and dishonest trade you have desecrated your sanctuaries. So I MADE A FIRE COME OUT FROM YOU, AND IT CONSUMED YOU, and I REDUCED YOU TO ASHES ON THE GROUND in the sight of all who were watching. All the nations who knew you ARE APPALLED AT YOU: YOU HAVE COME TO A HORRIBLE END AND WILL BE NO MORE.” Ezekiel 28: 16,18,19.
NEW KING JAMES VERSION – “By the abundance of your trading you became filled with violence within, and you sinned; Therefore I cast you as a profane thing out of the mountain of God; an[ I DESTROYED YOU, O covering cherub, from the midst of the fiery stones. You defiled your sanctuaries by the multitude of your iniquities, by the iniquity of your trading; Therefore I BROUGHT FIRE FROM YOUR MIDST; IT DEVOURED YOU, AND I TURNED YOU TO ASHES UPON THE EARTH in the sight of all who saw you, All who knew you among the peoples are astonished at you; YOU HAVE BECOME A HORROR, AND SHALL BE NO MORE FOREVER.” Ezekiel 28: 26,18,19. Both the NIV and the NKJV present this event as something already done and in the past in direct contrast to the KJV, and in direct contradiction to Revelation 20:10 which states that the devil will be cast into the lake of fire after the 1000 year millennium. Which version manifests the Spirit of truth, and which shows that it comes from the father of lies?
THE SANCTUARY/1844
KING JAMES BIBLE: “Neither by the blood of goats and calves, buy by His own blood He entered in once INTO THE HOLY PLACE, having obtained eternal redemption for us.” Hebrews 9:12. In accordance with Advent truth, this verse harmonizes with the Sanctuary message that Christ did not enter the Most Holy Place until 1844.
NIV VERSION – “He did not enter by means of the blood of goats and calves; but HE ENTERED THE MOST HOLY PLACE once for all by his own blood, having obtained eternal redemption.” Hebrews 9:12
NEW KING JAMES VERSION – “Not with the blood of goats and calves, but with His own blood HE ENTERED THE MOST HOLY PLACE once for all, having obtained eternal redemption.” Hebrews 9:12.
Both of these versions attack the Advent message pillar of 1844 by indicating that Christ went into the Most Holy place at His ascension. Were these versions written under the inspiration of the Holy Spirit, or under the inspiration of demons?
THE STATE OF THE DEAD
KING JAMES BIBLE –“The Lord knoweth how to deliver the godly out of temptations, and to reserve the unjust unto the day of judgment TO BE PUNISHED.” 2 Peter 2:9. This verse clearly tells us that the unjust will not receive their punishment until after they have been judged.
NIV VERSION – “If this is so, then the Lord knows how to rescue godly men from trials and to hold the unrighteous for the day of judgment, WHILE CONTINUING THEIR PUNISHMENT.” 2 Peter 2: 9.
NEW KING JAMES VERSION – “Then the Lord knows how to deliver the godly our of temptations and to reserve the unjust UNDER PUNISHMENT for the day of judgment.” 2 Peter 2: 9. Both of these versions give credence to the Roman Catholic doctrine of purgatory.
3 ANGEL’S MESSAGE/RIGHTEOUSNESS BY FAITH
KING JAMES BIBLE – “Because STRAIT is the gate, and NARROW IS THE WAY, which leadeth unto life, and few there be that find it.” Matthew 7:14.
NEW KING JAMES VERSION – “Because NARROW is the gate, and DIFFICULT IS THE WAY which leads to life, and there are few who find it.” Matthew 7:14. Here the NKJV not only changes “strait” to “narrow,” but replaces “narrow” with “difficult.” The implication of this is that if something is difficult you just try––just work a little harder and you’ll eventually make it––or in other words, Righteousness by WORKS, not Righteousness by FAITH––which is the 3 Angel’s message in surety. A teaching of Divine truth, or satanic falsehood?
THE HOLY SPIRIT
KING JAMES BIBLE – “Do ye think that the Scripture saith in vain, The spirit that dwelleth in us lusteth to envy?” James 4:5. This verse speaks of the yearnings and desires of the carnal nature.
NEW KING JAMES VERSION – “Or do you think that the Scripture says in vain, ‘The Spirit who dwells in us yearns jealously’?” James 4:5. By substituting Spirit for spirit this version declares that the Holy Spirit leads one to sin. Again, is this blasphemous substitution indicative of holy inspiration or satanic manipulation?
CONCLUSION
Nine of the “scholars” that produced the NKJV were also on the translation committee of the NIV. Is it not reasonable then to suppose that their attitudes, their opinions, their beliefs were no different when they translated the NKJV than when the produced the NIV? The NKJV makes over 100,000 word changes from the KJV, and though they claim that it’s a superior and more accurate translation they state: “It was the editor’s conviction that the use of footnotes would encourage further inquiry by readers. They also recognized that it was easier for the average reader to delete something he or she felt was not properly a part of the text, than to insert a word or phrase which had been left out by the revisers.” [The New King James Bible, 1982, Study Edition, “The History of the King James Bible.” P. 1235]
Here the editors of the NKJV are encouraging anyone and everyone to delete something he or she felt was not properly a part of the text. So if you are reading along and you run across something you don’t FEEL should be a part of the text––just delete it!!! A candid revelation of the true spirituality of these men and by the way, other than the name, the NEW King James Bible has nothing to do with the King James Bible. That was a clever and extremely successful marketing ploy to sell more Bibles. If the publishers would have named it, for example, the New Thomas Nelson Edition of the Bible it’s very doubtful that as many would have been sold.
The supplied verses prove that the NIV attacks three of Adventism’s four pillars – the Sabbath, the State of the Dead, and the Sanctuary...."http://omega77.tripod.com/cs1gettingtobot.htm
and the changes aren't just on doctrine...
SOME OMISSIONS & DELETIONS IN THE NIV BIBLE
THESE CAN BE SEEN IN MOST VERSIONS AS WELL, EXCEPT THE King James Version
1. NIV in Luke 11:2-4 omits key parts of the LORD’S PRAYER.
2. NIV, in Isaiah 14:12 blasphemes CHRIST by putting Him in the place of Lucifer (devil).
3. NIV in Micah 5:2 says Christ has an ORIGIN, wrongly making Him a CREATED being.
4. NIV in Romans 1:29 omits “FORNICATION” from the sins listed with sodomy.
5. NIV in Exodus 20:10 & Colossians 2:14 attacks on the SEVENTH DAY SABBATH.
6. NIV in Ephesians 3:9 removes Christ from being CREATOR.
7. NIV in Revelation 22:14 attacks on COMMANDMENT KEEPING.
8. NIV in I John 5:7, 8 denies the TRINITY and DEITY of CHRIST.
9. NIV in Revelation 12:17 attacks on the REMNANT CHURCH’S IDENTITY.
10. NIV in Daniel 8:14 & Hebrews 9:3-4 attacks on the SANCTUARY DOCTRINE.
11. NIV in Matthew 28:20 & Matthew 24:3 PROMOTES NEW AGE MOVEMENT.
12. NIV omits “FASTING” 5 times, and weakens PRAYER LIFE 3 times (Matthew 17:21).
13. NIV 178 KEY portions of verses are deleted (example – Matthew 20:16).
14. NIV 17 ESSENTIAL verses are completely omitted (example – Matthew 18:11).
15. NIV omits names of JESUS 38 times, CHRIST 43 times, LORD 35 times, GOD 31 times and OTHER NAMES OF GOD 26 times. Therefore, total names 173 times....
http://www.beyeready.org/page9.html