I would say it is definitely still active. The major advantage is that it is a native mobile app. Many people I know really like Tapatalk - maybe because they are posting on forums, which are not responsive.
ED´s responsiveness is already very nice, however, it would be a great add on, which maybe convinces even more users to participate in a specific forum.
I am just building up a forum in order to migrate an active Yahoo Group later on, when its ready. So I want to make it as convinient as possible for them...