Greek (WH): αὕτη δέ ἐστιν ἡ αἰώνιος ζωὴ ἵνα γινώσκωσι σὲ τὸν μόνον ἀληθινὸν θεὸν καὶ ὃν ἀπέστειλας Ἰησοῦν Χριστόν.
Previously, John 17:3 in the NWT read this way: "This means everlasting life, their taking in knowledge of you, the only true God, and of the one whom you sent forth, Jesus Christ."
2013 Revision: "This means everlasting life, their coming to know you, the only true God, and the one whom you sent, Jesus Christ."
Did the older translation mean to imply that head knowledge is all someone needs to have eternal life? Does head knowledge alone save us? Could someone get eternal life without knowing a lot about God?
We can answer the first two questions negatively, but the third question, affirmatively.
1) We need more than head knowledge in order to get everlasting life; a lot of people can memorize Bible scriptures, places, names, and even how the verse should be applied. However, that is not enough to obtain everlasting life.
Even back in the 2/15/1975 WT (pages 113-119), these remarks were made:
Getting to know God, then, involves knowing both him and his Son. Jesus Christ pointed this out when saying in prayer to his Father: “This means everlasting life, their taking in knowledge of [or, “knowing,” An American Translation] you, the only true God, and of the one whom you sent forth, Jesus Christ.” (John 17:3) Such “knowing” of God and his Son is not just head knowledge, acquired information. It actually means to recognize the authority of God and his Son and to submit to it.
Two points we can extract from the paragraph above is that "taking in knowledge" then meant, "knowing" God, not just knowing facts about him or his Son. Secondly, the WT clearly states that head knowledge is not sufficient: one must know God and his Son.
2) As a Witness, I've been taught that it's not just what someone knows but how much a person loves what he/she knows about God. We take in knowledge of God in order to know him, not just know about him. Furthermore, knowing God means obeying his commandments--putting into practice what we learn. See Hosea 4:6; Philippians 4:8-9.
To illustrate, a man might get to know facts about a woman, whom he wants to marry: he learns her likes, dislikes, facts about her family and how she feels about children, handling money and how she relates to her family. Without acquiring these facts, could the man ever come to know the woman? Yet the acquisition of facts would not be enough to know another person: it's necessary but not sufficient. We can say the same for our relationship with God.
While I think NWT 2013 improves the former translation since it captures the inceptive and telic aspect of the verb in John 17:3, I do not believe the older rendering meant that knowledge was sufficient without knowing God. That simply is not true.