When I use the tapatalk app it is the free one.I do log in directly from tapatalk if away from the desktop and using any of my mobile devices.
I have my ipod touch which is getting rough around the edges,but it always worked great for posting a photo direct from the yard at the hives over my wifi . I find the app itself works just as well from my Nexus 7 and android phone. I received the nexus 7 for a birthday gift a couple years ago and it was the version with only the camera facing the user so it doesn't get used as often for taking pictures.
I find tapatalk easier to use on my mobile devices for reading the forum than any of the browsers on the mobiles. It may be a personal feel for it ,I don't know, but it seems easier to work .
I have not been using the mobiles out in the beeyard as much,as I am usually in the house when moderating the forums and a 22 inch monitor on the old desktop still trumps the others,but hey I can't take it outside. :)
Bt in a nutshell, try the free one,then see what added benefits are there for the paid version. I have not looked into the upgrade in a while,but I may have to study it!