I think this is a very helpful book for the relatively mature Christian who knows the scriptures reasonably well. I wouldn't recommend it (at least without a mature mentor) to a new believer. You could go wrong and end up in a bit of confusion if you don't already know the sorts of things God is likely to say.
I didn't care about the guided imagery part. It seemed silly to me and also could be taken in the wrong direction. God has given me images in my mind as I have meditated on various portions of scripture, or immersed myself in worship or contemplation, but this is not the same thing as trying to conjure up something on your own--such as a picture of Jesus speaking to you. I guess it's okay if it works for you. I'm not sure it's dangerous or anything, as some have said. It just doesn't do anything for me.
I thought all the charts and quizzes were silly and a waste of time. The charts don't hurt anything, but I felt the results of the quizzes tended to be misleading and of questionable value and accuracy. As for the right brain/left brain thing, if you know what this means, you can probably already guess which you are--logical or intuitive. There are free on-line tests for this which are at least as good and a whole lot easier to take and to score.
The thing about the book that was the most helpful to me was the idea that God speaks to us in a flow of spontaneous thoughts that just "pop into our heads from nowhere." Such as when we get the urge to pray for a certain person, for example. Also, the examples of other people's journaling and what they had heard from God. Most of this stuff involves God speaking stuff to them that's basically straight out of the scriptures. At first I thought it was just their own minds supplying them with scriptures they already knew. Fine, but hardly supernatural.
I do get a little more specific instruction when I need it, but now that I've actually experienced God speaking the scriptures back to me, I understand how helpful it is. You can know a thing with your head and still not understand it with your heart/spirit. When God speaks the word to you, it changes you.
Overall, I think the book is worth reading as long as you do the exercises and as long as you keep to the bits you're comfortable with. I know I wouldn't be at the place in my relationship with God if I hadn't read this book, and that's why I gave it four stars. As much straw and stubble as there is in this book, the treasures hidden in the straw make it more than worth the read.
I'm ordering Virkler's DVD series for my simple church. As imperfect as his teachings are, they're the most effective and best I've found. If you know of better, practical instruction, I'd love to hear about it. Other works, like Madame Guyon's writings, Brother Lawrence, etc., are possibly deeper, but I've found them not to contain a lot of instruction that I was able to process and implement in my own life. They are inspirational and worth reading, but this book provides, for me, a better jumping off place for the beginner.