There is a companion volume called "A Guidebook to Mechanism in Organic Chemistry: Solutions Manual." If you are self-studying, this is a mandatory pairing. Sykes’ questions are notoriously "thinky," and having the path to the answer is invaluable.
The text reads like a lecture. It guides you through the transition from simple substitution to complex rearrangements with a conversational yet rigorous tone. Buying Guide: What to Look For
Because this book is a "student bible," used copies are everywhere. Look for "Acceptable" or "Good" condition on sites like AbeBooks or ThriftBooks. However, check for heavy highlighting—this is a book people love to mark up.