At the range I've heard the younger semi-auto generation refer to revolvers as "Old guy guns". That's fine. I'll take that (while muttering "ouch" under my breath).
Revolvers are generally very adequate firearms for civilians who will seldom see gangs or rarely have to deal with more than 3 thugs. For most law-abiding citizens, that's the majority of us.
To those who say the semiauto can put more fire downrange faster than a revolver, I will point out that this may be true only for average shooters. The auto can deliver more rounds in a few seconds, but those first 5-8 rounds can be fired faster by a
revolver. Look up Jerry Miculek's 12 rounds in 2.99 seconds. Or Ed McGivern's 6-shots in 9/20ths of a second!
Not undergunned
The revolver today is still the same or similar to your grandfather's gun. The ammunition is much more effective however (e.g. .38 Special +P). The use of the revolver does require more attention to marksmanship and proper technique than do many semi-autos. Yet, as difficult as it may be to shoot a DA revolver well, it seems to work just fine in the hands of many civilians during self-defense shootings.
I've talked to officers about revolvers being used by elderly women who have almost never fired a gun, by young wives defending their children and even a few teens and pre-teen children using revolvers defensively. Many of these ended fatally for the BG and in all but one case ended up causing an immediate end to their aggression. Under stress, the simplicity of their "point and click" interface helps a great deal.
The revolver isn't dead. Not yet.
There are advantages to the semi-auto platforms that give it an obvious leg-up for carry and defense. But they have numerous points of failure - magazines, feed ramps, bullet-setback, FTE, limp-wristing, out-of-battery conditions etc. Revolvers are simply less likely to experience failures when firing.
Revolvers can and do pack a lot of power into a small package. Large revolvers can pack enough punch to bring down bear or punch through automotive parts easily. This gives some revolvers a big edge over autos.
S&W Model 657 - aka "Night Sun"
If you live in an area infested with gang vermin and gang violence is a very real thing in the areas you frequent, a semi-auto may very well be your better choice. But only if you can shoot it well, there's no sense in
hoping one out of your 15 rounds hits the mark. Remember that speed is fine, but accuracy is
final.
As for me, revolvers are my favorites and still quite often a CCW companion. However, in higher risk areas I may switch to a favorite semi-auto for the ability to reload faster if the need arises.