Keep in mind that the original was written back in 2000. So most of the ideas in the book are pretty much mainstream these days. The second edition should be pretty interesting because of the move away from being class-centric.

When I was in college, I read "Refactoring to Patterns" which pretty much sums up Refactoring in a short chapter. The ideas aren't really that complicated, but seeing some practical examples is pretty useful.

[1] https://www.martinfowler.com/books/r2p.html