I am not going to claim that it is either of those, except possibility impressive to Ms Right, depending on who she is.

But it will help you get consulting gigs if you can say you wrote a book about X, where X is somewhat related to the consulting.

Whether that is worth it to you, is obviously something you would have to decided. I would by any book about how to run a small software company, organic seo, ab testing with rails or similar you write and I do believe many other here would too.