E-books do have a bit of a reputation of being connected to scams and dodgy schemes, but they are more popular now than ever before. Theres a much greater potential audience for them than ever before and as long as your e book is good quality it will be a benefit to you. Promoting freebies such as this on social media is free and easy and the more unusual and eye-catching your book is, the more attention it will get for you.
I think they've become played out. I would venture to say that most people are aware that they are simply bait to get you on a site's mailing list, after which they can anticipate a flood of daily emails nagging them to sign up for something or buy something. I absolutely dread when I get put on someone's "email drip" campaign, because it's several weeks of non stop constant automated emails pretending to be all warm and personal with me, drip feeding me silly superficial tips along with pushy sales pitch language. Not only is it a constant nuisance and distraction when I am trying to get work done, getting a bunch of email notifications like that, but it's also blowing up my phone while I am out and about at the store or driving. Worse yet, many of these make it impossible to unsubscribe from them, either with a fake unsubscribe link at the bottom which ultimately never works, or they just don't offer one at all. So I end up having to write another filter rule in Gmail to auto delete anything coming from them as a last resort, and report them as spam to Google.
I don't really see the point of taking information which would otherwise be a great series of posts on your site which can demonstrate your expertise to a much wider audience more readily, and hiding it in an impractical eBook, and forcing people to sign up to get it. Plus, Adobe Acrobat is annoying as well. Every time you launch it or do anything with it, it keeps placing itself in your task bar permanently and adding itself to your autostart, then nagging you about updates.