Glory
On the criminal investigation side, you won't get much recognition from the general public, since most people aren't aware that Secret Service agents perform that kind of work.
If you apprehend a really bad dude, break a money laundering or securities fraud case wide open, or expose a foreign exchange scam, you'll get some kudos from the other good guys involved and maybe even a plaque with a star on it. Then it'll be tomorrow, and it's back to what have you done for US lately?
Recognition for your protective work is a different story. It's really kind of bizarre that you don't get any recognition for your long hours, personal sacrifices, and job risks you undertake every day—but if you thwart one measly little attack on the president, everyone wants to shake your hand.