its not been released yet…
but Ive got one as a kind of ‘beta tester’ - its really cool!
currently there are a couple of apps, the primary one being a midi monitor tool which is very handy,
but you can also easily develop your own, so as you say midi fx should be simple enough.
as you can see, it has a midi din in and out, and also it acts as usb midi device - so could act as a bridge - or do all sorts of interesting things e.g. generator midi?
i think midiboy is going to be a diy build only (not sure though) , but its very simple and quick to do - iirc took me less that an hour to do, and the instructions were simple to follow.
as others mentioned Blokas also have MidiHub ‘up their sleeves’ which is even more interesting for midi fx (imho)
not sure on release plans of either,
I guess midiboy is easer, as its simply a kit…
MidiHub is very stable, though they just added a few more features to the software - so perhaps they were waiting for those before release - but really don’t know.
but yeah, blokas having been doing cool stuff… e.g. releasing Patchbox , and lets remember they are behind patchstorage.com too… so really ‘giving’ to the community 
EDIT: ah, just noticed they’ve put it on the front page …
so i can also say, indeed, its also working as a controller for Orac, when Orac is running on the rPI 