I’ve now had a change to get some games on this app and its hugely impressive, in fact the only point of confusion I had was when artwork was not added for a game and this is easily fixed by long pressing (3D Touch) a game, tapping select change artwork and then using either a file on your system/phone or by using the games database search option.
You can also rename games in similar manner, long press, rename - the games themselves are hashed on the device (phone) so renaming and artwork is all handled via a database - so go nuts with the new artwork and renaming.
First impressions of the app are that it is very smooth, very quick and frankly very obvious in the way it works, no complaints at all.. although I’m not sure syncing works between desktop and mobile - when using Google Drive.. at least it did not work for me.
I’m not much of an emulation person myself so in terms of the quality of the emulation - someone else will have to tell me, but so far I see no lag (except maybe a few stutters on Mario Kart 64) and the sound seemed to be very much in sync with what I was seeing… in short so far so good.