What I did poorly: I'd written the book's sample before I ever put it on leanpub. Before a book is published you can collect contact and price information from those who are interested. However, once you publish and begin selling, you no longer have the ability to collect the previously mentioned information. I published and began selling my book immediately - and forfeited my chance to collect that information.
What I did well: I published early and often. I can't say enough nice things about leanpub. I've gotten tons of feedback on example style, writing style, typos, and content. One reader's suggestion to switch to Kevlin Henney's Java formatting style made my book enjoyable to read on a Kindle. I had twitter followers apologizing for "being pedantic and pointing out typos", and I couldn't have been happier to get the feedback. Each typo I fix makes the book more enjoyable for everyone. If you're going to write a book, get it on leanpub asap and start interacting with your audience.
What I learned from Refactoring: Ruby Edition (RRE): RRE contains errors, far too many errors. I vowed to find a better way this time around, and I'm very happy with the results. Every example test in the book can be run, and uses classes also shown in the book. However, writing about tests is a bit tricky: sometimes "failure" is the outcome you're looking to document. Therefore, I couldn't simply write tests for everything. Instead I piped the output to files and used them as example output in the book, but also as verification that what failed once continued to fail in the future (and vice versa). WEwUT has a script that runs every test from the book and overwrites the output files. If the output files are unchanged, I know all the passing examples are still correctly passing, and all the failing examples are still correctly failing. In a way, git diff became my test suite output. I'm confident in all the code found in WEwUT, and happy to be able to say it's all "tested".
What's unclear: Using leanpub was great, but I'm not really sure how to get the word out any further at this point. I set up a goodreads.com page and many friends have been kind enough to tweet about it, but I don't really have any other ideas at this point. I've reached out to a few publishers to see about creating a paperback, and I suspect a print version will increase interest. Still, I can't help thinking there's something else I should be doing between now and paperback launch.
What's next: The rough draft is 100% complete, but I expect to continue to get feedback over the next month or so. As long as the feedback is coming in, I'll be doing updates and publishing new versions.
If you've already bought the book, thank you for the support. It takes 10 seconds to get a pdf of any book you want these days, and I can't thank you enough for monetarily supporting all the effort I've put into WEwUT. If you haven't bought the book, you're welcome to give the sample a read for free. I hope you'll find it enjoyable, and I would gladly accept any feedback you're willing to provide.