I did a bit of looking through the SMF modifications for mobile-responsive themes and was sadly unimpressed. Tried a few of the 'popular' ones and they looked fairly terrible, and wouldn't play well with our modifications/plugins. So, sadly, no native mobile-responsive theme will be available here.
Tapatalk is the one to use, although I don't much care for it either.
I find browsing in landscape mode on my phone works best for me. Normally I use a PC or my iPad, and both work well enough.