I've owned this book for several years...been dying to make an earth oven since I bought this. FINALLY we got around to it this year and even though ours is a simple dome, the pizzas that come out of that oven are to die for. We've also made bread to rave reviews but have yet to do much more with it. It is worth it just for the pizza, though; you CANNOT get pizza like this any other way. Pizza stones in an oven just do not cut it.
It probably took us about 20 hours all told to build our earth oven, working in teams of 2 over a period of about a week. We built a permanent base of concrete blocks for our oven, topped by firebrick and then the dome. It was well worth the time invested.
I have a couple of minor criticisms of the book. First, it is a bit confusing on the whole "will your local earth work" to make an earth oven question. There's a way to test your soil by letting the layers of dirt and clay etc. precipitate in a glass of water - did not work for us. It showed a very low clay content. Yet we could do the squeeze test with the dirt (detailed elsewhere) and it appeared to be very clay rich. Anyway we ended up using our local dirt as is based on the squeeze test and observation of the dirt, just adding a touch of straw as directed and the oven turned out great. It will probably need patching or replacing in a few years but it does the job fine. Second, I found the instructions a bit disjointed when it came down to actually making the oven. It seemed I had to keep skipping around to find answers to different questions. If the author writes a new edition, I hope he will make the whole thing more linear.
Bottom line, though, is that this is a fabulous resource and inspiration. I LOVE my earth oven and I kiss the feet of the author for spreading the word. :)