I want to create a book in PowerPoint
You may or may not want to do that. It depends on the type of book you're talking about.
Let's talk about the usual kind: printed books with more than a trivial number of pages. If that's what you have in mind, you should consider a different program for the job. Here are a few reasons why (and a few reasons why you might reasonably want to ignore our reasons).
PowerPoint won't "flow" text
PowerPoint won't "flow" text from one page to the next. Imagine that you have a many-page book and you make a last-minute change to the text on page 3. Ooops, that pushed a line of text off the bottom of the page. So you copy the last line of text to the beginning of the next page and ... oops. The last line of THAT page just went off the bottom too. Fixing one little change like that might "ripple" all the way to the end of the book, with you manually fixing each page one at a time. You might be finished just in time for the next "one more little change on page 3".
Of course, if it's more of a picture book with little or no text, this wouldn't be such a problem.
Color "space" problems
PPT only thinks and works in RGB color; printing presses work in CMYK. The conversion from one to the other can really mess up some of your colors. Your printer can tell you more about what's needed for their processes and whether they can accept RGB input or not.
Of course, if you're printing to a desktop printer, then ignore that problem too.
Laying it out for printing
Books are usually printed in batches of folded sheets. Each sheet is big enough to hold four or more printed pages (two or more on each side). In order for the pages to be in order once the sheets are folded and bound into a book, you have to print them in an unusual order. For example, for a 32-page book, the first sheet would have Page 1 on the right side of Sheet 1/Side A, and Page 32 on the left side. The other side of Sheet 1 would have Page 2 on the left side and Page 31 on the right side.
A commercial printer may have software that automatically does this kind of layout for you (it's called "imposition" by the way). Better desktop publishing software does it too. PowerPoint won't. If you plan to print it on your own printer, then depending on the capabilities of your printer, it may be fairly simple. Or it may be complicated enough to make your head explode. Do some tests before you make any final decisions.
Not you, the pages. Page creep happens when you fold a stack of more than just a few pages.
To get an idea of how it'll affect you, work out how many sheets your book will take, take that many sheets of the type of paper you plan to use and fold it in half.
See how the inside pages stick out at the unbound edge?
Commercial printers and binders trim the book to even that out but that also means that the inside pages, if printed with the same margins, won't appear in exactly the same position. Good desktop publishing software (or at the printer, imposition software) will take care of that automatically. In PPT you'll have to work out for yourself how much to adjust each page and manually move everything around to compensate.
Keep in mind that PowerPoint has no page margins you can work with to make this simpler. It's all going to be manual.
Again, if you don't have elements that need to appear at the same place on every page, this may not be an issue for you. You might decide to live with a bit of page creep.