There are lots of ideas about what God is like.
If you wanted a Christian perspective then it is fairly straightforward: everything Jesus did or said is what God does or says.
Ross Ciano (a former youthworker for Bishop Hannington Church in Hove) said in an interview that:
If you wanted to find out what God is like, look at Jesus. If God were to look in the mirror, he would see Jesus.
According the the Bible, Jesus is the mirror reflection of God.
Ross is referring to this passage in the Bible:
The Son is the radiance of God’s glory and the exact representation of his being. Hebrews 1v3
Radiance means glow, or reflection. The claim in the Bible is that whenever Jesus does something he is the reflection or glow of God himself. When you see the one you are seeing the other.
This is very useful for us if we are trying to find out what God might be like - all we need to do is look and see what Jesus did and hear what he said.
What did Jesus do and say?
The 8.30 PMT DBRA diagram is really useful for listing all of the main events of his life. Here is an overview of all the miracles in John's Gospel. Jesus said a lot during his ministry and it isn't hard to uncover some of these things for yourself. The Sermon on the Mount is a great place to investigate if you want to sample some of Jesus' teaching. It is an extended sequence of recorded teaching/preaching that has much of God's thinking on show.