If you are truly talking about pocket pistols (i.e., those that are carried in a pocket and not in a holster), then both semis and revolvers have their pluses and minuses.
Autos:
* Mini-autos are more finicky about ammunition, grip, and everything else that can occasionally plague a full size auto. The further you shrink the size and attempt to maintain a full power cartridge, the more exacerbated any small issue will become.
* The small size and grip frame can make practicing with and controlling a full power cartridge capable pistol difficult.
* Until you get to the P3AT/LCP size, weight can be an issue with them. The shrunken 1911s are a perfect example of this.
* The autos can't be fired more than once from inside a pocket.
That said, reloads in a new magazine carry and conceal well. The smallest autos in .32 and .380 are light years ahead of where they were in terms of concealment and effectiveness over similarly chambered pistols just 20 years ago. There are several true pocket pistols available today in calibers up to and including .45ACP; something that was unthinkable not long ago. The carry flat, if the overall size is conducive to pocket carry. The semi-auto platform is one that most people who shoot today are familiar with and thus "cross training" is easy.
Revolvers:
* The are generally thicker and can print more easily due to the girth around the cylinder.
* They generally have less rounds in a single load (5 to 6 vs. 6-8).
* Reloads carried in a speedloader don't conceal well at all.
* Revolvers are not commonly carried or used today by most shooters.
* Recoil in a true pocket sized revolver can be an issue.
That said, ammunition reliability problems are generally avoided in revolvers. True, it may have one or two that it shoots better than others, but feeding and reliability are not a normal concern. The standard revolver calibers of .38 Special, .357 Magnum and .44 Special are the most common revolver chamberings and they have a long track record of success in defensive use. The concealed hammer or shrouded hammer revolvers can be successfully fired multiple times from within a pocket without jamming, and they are also quite slick to draw from a pocket without snagging.
We truly live in a golden age of firearms. If you had wanted a true pocket pistol 40, 30, or even 20 years ago, you were stuck with just a couple small revolvers or sacrificing power to get into a .32 or .380 that quite often had reliability issues in addition to marginally effective ammunition. Today, you have your pick of dozens.
I personally think that they both have their place and their values. I've carried the smaller .380s for a good number of years, as well as a 442/642. I don't find it that difficult to conceal a full sized pistol these days due to great belt and holster options, but the little guns still have their place. Pick one that works well for you; get used to it; carry it; and don't worry about what someone else thinks.
