Heaven is where God is. He is the light of heaven, the joy of heaven. As you mature in your understanding of the Bible, you realize there is no material concept of heaven that will do it justice. The Bible talks about streets of gold as clear as crystal and walls made out of precious stones (see Revelation 21:18-21). All sorts of images immediately come to mind when we mention heaven. More than anything else, heaven is a spiritual condition where one spiritual being is in touch with another spiritual being, and there is total communication and fellowship.
Whatever we consider to be a joy here on earth will be heightened millions of times beyond anything we can conceive when we get to heaven. The apostle Paul put it this way: "Eye has not seen, nor ear heard, nor have entered into the heart of man the things which God has prepared for those who love Him" (I Corinthians 2:9).
In the Middle Ages philosophers talked about the "ultimate good." The ultimate good to them was being in the presence of God. That will be the greatest aspect of heaven. Those who are there will be in His immediate presence, in a way no one can possibly know this side of eternity.
Being in God's presence will bring an intensity of delight that will far exceed anything we could know here on earth. Furthermore, in heaven there will be neither death, nor sorrow, nor sickness, nor poverty.
"He will dwell with them, and they shall be His people, and God Himself will be with them and be their God. And God will wipe away every tear from their eyes; there shall be no more death, nor sorrow, nor crying; and there shall be nor more pain, for the former things have passed away" (Revelation 21:3-4).
The Bible also talks about crowns and thrones in heaven, so we do know that heaven is not just a huge democracy where there is no differentiation of function (see Revelation 4:4-11). There will be different functions and different levels of responsibility assigned to different people. For there will still be levels of order and structure throughout God's universe.
The Bible says that those human beings who are fortunate enough to enter into heaven will actually judge angels (see I Corinthians 6:3). The fallen angels--or demons--will come before us and we will decide their fates. Perhaps people will be assigned to watch over a planet or two. We do not know for certain what tasks we will be performing in heaven, but there will obviously be an ongoing, functioning universe. We will be God's messenger-agents in ordering and running it.
There are many things about heaven we do not really know. Will there be animals in heaven? The Bible says that Jesus will be riding on a white horse when He returns to reign on the earth, but we do not know if this is a literal horse (see Revelation 19:11). A white horse represents purity and power, so this may be symbolic. We cannot say for sure if there will be animals of any kind in heaven, but there may be.
We do know that we will be able to recognize our loved ones in heaven, and we will experience great joy over being reunited with them (see Luke 23:42-43, Hebrews 12:22-23). Your real self will live on in heaven, not some shadowy part of you. You will never feel so alive as when you enter into the heavenly city, the New Jerusalem God has prepared for the saints.
There is also going to be an extension of man's mind beyond anything we could begin to understand now. There will be an opening of understanding into the secrets and mysteries of the universe. Furthermore, in heaven there will be no fear of any kind of evil, and God will provide magnificently for His people.
What is heaven like? It is better than anything any human being could ever imagine when he tries to picture the best thing that could ever happen to him. Beyond that, there is not much else we could say!