What is eternity or heaven going to be like according to this teaching?

Les teaches that God’s promise to David’s house and kingdom being established forever shows that God was looking beyond Israel’s little kingdom under David and Solomon; it is the beginning of eternity’s promises. The earthly kingdom promised to Israel has a time limit in Revelation of a thousand years, called the millennium, a definitive period. But that thousand-year reign of Christ is merely the introduction for the eternal setting. Revelation chapter 21 brings a new heaven and a new earth, and the whole kingdom economy will move right on into eternity. Les explains that this gives a better concept of what heaven will be. He recalls that when young, it almost scared him that heaven would get boring—sitting on a cloud, strumming a harp, doing nothing but shouting hallelujah or holy, holy, holy. He says that will certainly be part of it, but eternity is going to be a viable exercise, a place of intense activity, albeit without all the problems, tribulations, and sorrows we have now. So heaven is not to be viewed as boring and monotonous; it is quite the opposite.