Answer: It is probably one of the poorest imitations of the Bible on the market today! The NIV has about 64,000 words missing from the Majority Text. Here are a few of the many verses they removed: Matthew 17:21; 18:11; 23:14; Mark 15:28; 11:26; 9:44; 9:46; Luke 23:17; John 5:4; Acts 8:37; 24:7; Romans 16:24.
Many times they failed to translate the Hebrew or Greek words; so, unless you know Hebrew or Greek, you would have no idea what you are reading. For example: Check Genesis 6:4 where the Hebrew word "nephilim" appears. Or refer to Matthew 16:18; Revelation 1:18; 6:8; 20:13; 20:14 where the Greek word "Hades" appears.
The best translation we have is the King James Translation of 1611, bringing the Hebrew, Greek, and Aramaic into the English. The KJV has a Fifth Grade reading level, whereas the NIV has an Eighth Grade level. In the KJV about 95% of the words are one and two syllable. To copyright the NIV and avoid plagiarism, they had to change, add to, and omit many words and verses. They want your money, not the word of God!
"Every word of God is pure:...Add thou not unto his words, lest he reprove thee, and thou be found a liar." (Proverbs 36:5,6).
It is best to heed the advice found in Acts 16:31,
"Believe on the Lord Jesus Christ, and thou shalt be saved."