The Winter 16 (API 35) release has no substantial impact on the accuracy and recommendations in the book.
Details on Individual Changes
Running individual unit tests
Chapter 10 – You can now run individual tests in a test class! The book noted that this was possible using the tooling API and expressed a hope that it would be soon available in the UI. Our wish has been granted.
Roll0up Summary field Limits
Chapter 11 – You can now have 25 roll-up summary fields on an object. You can have up to 7 external ID fields.
That said, the recommendation to avoid using these field types in a managed package stands, as these limits are global to the object and not specific to each package.