Simple and sturdy. I have it for few years now and use it mostly with synth/workstation. I got another one, fancier and more expensive purely for digital piano and after 2 years it failed, so I took that cheap Yamaha FC 5 out of my box and it still does the job.
The original sustain pedal for my YAMAHA P-255 is just to bulky to carry with in a keyboard bag. I bought the FC5 pedal as an lightweight alternative for the road. This pedal has not the same feeling as the FC-3A comes with but it is absolutely enough for my gigs in a blues-rock band. When playing classics I definitively would go for the FC-3A instead. Again it is a bit pricey compared to other offers. But this is what you have to take when choosing original manufacturer parts.