The thing about FIE is, they were an importer. Some were good, some were bad, most were made in different places. So it's hard to ask "are FIE guns any good?" They tended to be lower in price but that doesn't necessarily mean a rotten gun.
The country of origin will be marked. It will most likely be German, and the German SA wheelguns of the '60s and '70s were mostly pretty decent. That whole business moved to Italy later, and the Ubertis and Piettas of today are mostly better than the old German stuff but in some cases, not by a lot.
Anyways. A German FIE was probably a JP Sauer and Sons gun, which were fair to good. It *might* be a Rohm, but believe it or not the Rohm single actions were better than the horrible double actions that just blew chunks.
Still not "heirlooms" but fair if you want a plinker/practice rimfire gun.