This is a very professionally produced booklet and CD. The contents fall into 4 categories:
1) A 'primer' for Xaphoon beginners
2) General recommendations
4) Concluding remarks.
The primer covers all the basics of how the instrument works and how to get sounds from it. There is no fingering diagram which is, I feel, an oversight and is worthy of 1 star being deducted. (Especially as the fingering is known to be unusual at times). The descriptions of how to play are clear but I'd recommend you supplement these by searching YouTube for demonstrations.
Generral recommendations simply summarise the primer and add a few general tips.
The songs are well-graded and sequenced and are all related to the contents of the CD.
Concluding remarks simply summarise the contents and overall aims of the booklet and CD.
As for the CD, each of the 9 songs is played twice - first featuring just the Xaphoon and then with just the backing track.
There are many performances and demos of the Xaphoon on Youtube and some of these do look at breathing and fingering. There are also uploads which feature some of the contents of this booklet.
Used in conjunction with those, this book is a really useful resource and I have no problems recommending it - but do be aware that playing the Xaphoon well takes a lot of practise and quite a lot of time.