There is a whole lot of spiritual/mystical wisdom packed into this little book, and Tony D'Souza's translation makes it easy to understand. Originally published as the "Theologica Germanica", it was discovered in a monastic library in 1516. If you enjoy reading the mystics, this is a must-read.
Also know as the Theologia Germanica. I have not read the other translations of this book, but I've read this one several times. One of a series of mystical treatises in the later middle ages by anonymous monks, but among such works, the Cloud of Unknowing is definitely superior. Still, The Way of Jesus is a very important and beautiful book.