I'm pretty much just confirming what the previous reviewer sad more knowledgably than me! It's best to work through this book with a more recent fingering chart, as Geisbert's fingerings often don't work well on a modern Baroque system recorder. (Even the lower octave B flat is dubious on mine.) That aside, this book is an excellent progressive collection of excercises, tunes and short pieces. The bits I've played so far have been both tuneful and well-designed as little studies. There's at least 2 years worth of material here for me.
This 79 page book for adult students of the treble/alto recorder is made up of 3 distinct parts. The final section is available separately as "15 solos by 18thC composers". I'm told they were written by JD Braun, though some music historians attribute some of them to Quantz. Giesbert describes them as a fairly easy introduction to baroque pieces. I've seen them described as grade 6 pieces, though I don't see why a grade 3 or 4 player should not play some of them slowly. The middle section is 77 exercises for finger and tongue dexterity, and though I've only played a couple I think they are less boring than many such exercises and lead credibly towards the final section. The main part of the book is for beginners to the treble/alto recorder, introducing one note at a time. The tunes that make up this section are often drawn from German and English folk and 16thC pieces. They are presented as duos for treble recorder, with the learner taking the top line and the teacher, if there is one, the more complex bottom line. People who are learning on their own will need to read music fairly well. The learning curve is quite steep - there are 140 exercises and exercise 124 is an Air by Purcell. A flaw in this section, which can be easily overlooked, is that Giesbert advises learners to use the buttress finger by covering hole 6 of the recorder. A little experiment will tell you that this will push notes well out of tune, so players these days use the right hand little finger above hole 7 for the buttress. Unfortunately this is not the only poor guidance in this section - for example on page 20 Giesbert tells us to play high C with fingers one and two, and high D with fingers one two and three. Because of these errors the book cannot be recommended to the complete beginner working alone. For adult players who are experienced enough to take the tunes and exercises without the poor advice, I think it is an excellent way forward. I plan to work through the book recording the top line on my phone and then playing the second part, and using the buttress finger - but not on hole 6!