It does everything on a mobile that you can do on a PC, I think.... not found anything yet anyway.
The only thing tapatalk users might want is the push notifications and the fact you can have notifications in the phone's own notifications systems. So a PM can appear and notify you just like a text message can and does. Sort of thing.
But to be honest that used to annoy me.
That all said. We're having our own branded version of tapatalk soon. Been talking about it for years, even paid for it monthly for years (x4 forums!!) and still haven't done it.