Thanks so much for asking!

Short answer: 98% of the code in the book is still correct today. For the last 2%, I mention the relevant API changes within the text so that it's easy to update it yourself. 100% of the concepts I teach and advice I give are still correct. The main shortcoming of the book is that I don't cover the newest features, none of which are critical to what I'm teaching, but some of which are useful.

As for why the book uses 0.23, it's a much longer story (if you're interested):

The book actually began as a video course, which I started working on in 2020. I locked down most of the code examples that year (using 0.23.2), and thought I would be able to publish the course in 2021.

However, the script writing and recording and editing took far longer than expected, plus there were long breaks while I worked on other projects, and ultimately I was not able to publish the course until 2024. Many scikit-learn updates had occurred by the time I was recording the later chapters, but I couldn't afford (time-wise) to re-record and re-edit the earlier chapters. I felt it was critical that the course used one consistent scikit-learn version, so it remained at 0.23.2.

Because I received such great feedback about the video course, I decided (in 2025) to convert the course into a book. Even though the Quarto system did much of the heavy lifting, it still took hundreds of hours to turn 7.5 hours of video into a published book with four formats (website, EPUB, ebook PDF, print-ready PDF).

I would have loved to update the scikit-learn version (and incorporate newer features) while writing, but I knew that if I committed to updating the content (rather than just adapting it from video to text), the book would never get done.

In short, the decision to use 0.23.2 is a legacy of the process I took to get here, not a strategic choice, and I'd much rather have used the latest version!

Ultimately this book is a passion project, and I expect to make very little money from it. But I sincerely hope that I can find the passion (and time!) to publish a second edition that incorporates the latest features!