Yes it works on WP 4.1

Yes it works, its very easy to configure too. It sits just below the Jetpack Share this buttons on the screen, and looks good. I’m running Avada theme. However, you will only see the link when viewing on a mobile – not on a PC or Mac. When Whatsapp go desktop (soon i’m sure) then it’d be nice if the plugin was updated for that. Finally another nice-have would be an addition to the contact form / contact7 so that could be whatsapp’d to me as an enquiry.