<grumble> Part of that is going to be Tapatalk's almost forced advertising. Unfortunately, to get Tapatalk to work with the forum, a display driver has to be loaded. I'm not surprised that they take the opportunity to say "Look who's using this!" I've also configured the server Tapatalk account to not display advertising, no, we're not interested in sharing revenue with Tapatalk's advertisers, we've got our own program.
It works pretty well for basic forum browsing. I will absolutely *NOT* upload any images with it, those actually get stored on the Tapatalk servers and BB linked. I haven't found the terms of service, I don't know if they are trying to claim ownership. It really doesn't have for moderation, and even less for administration. But it does work fairly well for general browsing. At least, the new version does. The old version had some pretty serious issues with crashes when looking at forum threads loaded with images.
Why does it work? It doesn't download HTML. I haven't disassembled the stream, but my suspicion is that it's a customized protocol. For instance, when loading this page in a browser, several dozen requests are made to the server. I'll bet that Tapatalk condenses that all down into a single request, and without all of the HTML cruft. I would expect it to work pretty well over a slow cell connection. On 4g, it flies.