I give the slide a yank with my thumb and forefinger; I think this is slightly faster than an overhand grip, but overhand should work fine as well, especially for those with less hand strength.
I'm a lefty, so depending on the exact pistol I might have a hard time hitting the slide catch even if I wanted to, but as with many controls on the "wrong" side I find there is actually some non-negligible advantages (some already mentioned):
1) "Slingshoting" works the same on all pistols; where as slide catches can be located in different places on different guns.
2) Requires a lesser degree of motor skill, which can be good under stress or in the cold where you may not be able to feel your fingertips well, or be wearing gloves.
3) No matter what I do with my grip, I can't ride the slide catch with my thumb, pushing it up or down and causing undesired operation as a result. I've seen many right handed people, including experienced shooters, do this at one time or another.