What is heaven?

Here's a shockingly powerful quote, quoted at challies.com.

The critical question for our generation--and for every generation--is this: If you could have heaven, with no sickness, and with all the friends you ever had on earth, and all the food you ever liked, and all the leisure activities you ever enjoyed, and all the natural beauties you ever say, all the physical pleasures you ever tasted, and no human conflict or any natural disasters, could you be satisfied with heaven, if Christ was not there?
John Piper, God is the Gospel