I bough this to use it to program my MIDI foot controller. I can already do this using my laptop via an M-Audio FastTrackPro. Using an identical setup - same laptop, same software, same foot controller, and simply replacing the FastTrackPro and cables with this device, immediately highlights the problems - the foot controller's programming is messed up (though in a predictable & reproducible way) and the programming software is receiving corrupt data back. Basically, this device doesn't handle SysEx messages correctly.
Many USB-to-MIDI applications won't need SysEx, so it may still be perfectly usable in other situations, but it doesn't support all MIDI capabilities correctly.