For anything other than a novel, that's usually the least representative sample. That'll give you the copyright, table of contents (admittedly useful) and the Preface and the Introduction and a page with a couple of quotations on it.

Not really great to judge the quality of writing / code samples or whatever you're interested in.

I always used to use zlib for "flicking through" a book the way you would in a bookshop to see if it was worth buying it.

We have a local chain that sells well curated used books and it's brilliant. Picked up my copy of Godel, Escher, Bach because I saw it on the shelf and flipped through and was like 'Yes, please!'

Note that this is only for print editions. For Kindle editions it does not have "Surprise Me". For those "Look Inside" seems to just show you the same sample that you get if you ask it to send a sample to your Kindle.

I've found this is often completely useless for music books and math books as the sample doesn't get far enough in to actually have any music or math notation, and it is terrible handling of such notation that often makes an otherwise good Kindle book unreadable.

I once bought a Kindle edition of "Proofs from the Book" and it had been produced apparently using OCR which didn't know how to handle anything other than normal letters, digits, and common symbols. Things like integral signs, summation signs, and set relationship symbols showed up as whitespace.

Another math book I bought had many of the equations as graphics. Reading on the Kindle app on a computer or tablet was fine. The images were scaled to a reasonable size and were quite readable. On an eInk Kindle however they were not scaled. They were tiny and required more magnification than my best magnifying glass had for me to read them comfortably. I had to tap them to get a menu that would let me show the image full screen. This made reading the book incredibly tedious both from the slowness of the Kindle and only being able to see one equation at a time this way.