I agree, the FPS is not that impressive. I've had my device since Thursday so in the 4-5 days I've owned the S10+ I had it ask to "press harder", "keep your finger pressed a little longer", "make sure your finger covers the entire senor" or just "no match" at least more than dozen times. I've even gone as far as registering my thumb as 4 separate finger prints.
And this is all post day 1 FPS hardware update. I'm not suggesting it's horrible but it's not "quick" or reliable by any means. At least not in my experience using it. I'm hoping that future software updates make the reading slightly quicker so that only a tap is required rather than a full 1-2 second press.
And keep in mind, it also requires you to use almost the full surface of your thumb versus just the end or tip of your thumb.