Unfortunately both the Sega Genesis and the Super Nintendo aren't a part of my history. So the appeal of this device isn't so great. However I'm a huge fan of emulators. I can safely say they are my greatest computer passion. So much, they have been responsible for me having learned how to program the Zilog Z80 processor, which powered the Sinclair ZXSpectrum, Apple II and Commodore 64, and that today still serves as a great processor for embedded systems (on many cases better still than the traditional, but more limited, PICs).
So I certainly can appreciate how cool this device is for anyone insterested on emulation of those two systems. In fact, for emulator fans this device may as well double as a great rom dump device for their cartridges. I sort of follow the progresses of emulators like Fusion, HazeMD and ZSNES (which handle these two systems) and I constantly hear of the dumping progress of hard to find cartridges. With this, anyone -- knowledgeable or not -- can make their own dumps easily when they own the cartridges.
Likewise, for anyone with just the roms, this functions as a sort of affordable controller port, which at $85 for the ability to use up to 4 controllers at once is a sure steal.