The dev doesnt seem interested in adding ePub 3.0 support when there are free alternatives that handle it just fine. Sure the UI is nice, but who really cares when 95% of your time in this app is spent actually reading a book. There was no reason for the dev to waste time on yet another ePub reader (Gerty) when he already had the superior app in Marvin, other than just to double-dip his customer base. His time would have been better spent on improving Marvin, but instead we ended up with 2 sub-par apps that rarely get updated, neither of which truly support ePub 3.0.
bonebox about Marvin Classic - eBook reader for epub