Jesus made this quite clear. He said that if we have seen Him we have seen the Father. When we read through the Gospels and we see what Jesus was like and how He conducted Himself, then we see what God is really like. We also see from 1 Corinthians 13, that God has all the attributes of love described there. John says that God is love, and therefore 1 Corinthians 13 actually describes the nature of God quite clearly. Also, we see in the fruit of the Spirit in Galatians 5, the nature of Christ and therefore of God.
From that we see that God is loving, joyful, peaceful in Himself, gentle, the kindest Person we will ever meet, faithful in all things, meek in that He is a gentleman in the way He handles people, absolutely good in every respect (Jesus says that the only good Person in the universe is God), and totally self-controlled in everything He does.
These things give a very clear and accurate view of the nature and character of God. He is not a mystery to those who know Him.