I remember downloading it like 6-7 years back and not liking it over individual emulators. Now though it's so easy to download cores and run so many different emulators under one application. It even has runahead latency reduction which is nifty, not to mention it's huge library of shaders.
Now the only problem I have is I can't find a good site for arcade roms that isn't some shady shit. Vimm's Lair, my usual go to, doesn't host arcade roms sadly.
Knowing nothing about the allegations, "code theft" of Free Software is still certainly a thing. It commonly comes in the form of stripping attribution and taking credit for other people's work. This is more common than you'd think.
oh if it wasn't attributed, it's a total violation of GPL