I always heard recoil was very low. Maybe a good choice for elderly or someone that has wrist/hand issues?
Maybe, likely influenced by the platform you are using. The FN FiveSeven recoil impulse is there but it is fast and minimal IIRC. I noted some exaggerated muzzle flip, but even that is manageable and would be tameable with some continued training. The flash and noise are the big signature items. Less than a true flash bang, but somewhere close.
I say maybe because the FN FiveSeven has an unusual Frame mounted safety. My short fingers were not going to reliably activate or de-activate it. As a two handed gun, there are certainly European military applications of the frame safety. it would be a two handed gun for most older folks, as the safety is not very proud either.
FN Five-seveN(R) | FN(R)
The Ruger 57 has a useable rear safety, based on a fondle-only session. I did find the front to back dimension too much, seemed more than the FN FiveSeven. Not in a hurry to shoot one.
The FN trigger is Glock plastic-y and mushy, but not terrible. I would describe it as better than any of the Gen 1 SW MP autos, a bit smoother. Comparable to the best stock Glock triggers, but more creep. That is also based on just a few guns. The trigger would work fine for most older folks I expect (I have some arthritis already and mild nerve damage in my hands).
The other plus is the FN was weight, as in airsoft or toy-feeling light weight. It may weigh the same unloaded as 640 and loaded as a Model 19, but it is stoked with ~20 rounds. The balance is awesome, just a bit biased to the rear when loaded. I cannot recall another revolver or high cap service pistol that feels as weightless. Almost no one should have a problem aiming correctly.
All in all, I would not buy a 5.7 cartridge gun until shooting one. The flash is serious and you should experience it before buying. That said, the limited supply of FiveSevens has kept the used prices pretty high.