John Richard Wimber was a musician, charismatic pastor and one of the founding leaders of the Vineyard Movement, a neocharismatic Evangelical Christian denomination which began in the USA and has now spread to many countries world-wide.
For someone like me, there was nothing new to be found in this book, but it would be a great introduction for new believers involved with a Vineyard-esque church.
I haven't read Wimber's other books, but after reading this less known one, I'm definitely interested in his others (Power Evangelism, Power Healing). There are definitely some nuggets worth mining in this book throughout, but I benefitted the most from the last two sections: "Depending on the Holy Spirit", and "Fulfilling the Great Commission"--Wimber's point of view on spirituality and unique testimony were a great encouragement to me.