I have owned both the PPK/S and the Sig P238.
FOR ME:
PPK/S was more accurate and precise than the P238.
P238 slide was easier to rack.
P238 felt recoil was less.
PPK/S is flatter and prints less (isn't as noticeable in a pocket).
PPK/S has a safety and a de-cocker.
.380 ACP (or 9mm short)
Obviously not as potent as a 9mm parabellum.
.380 ammo is more expensive than 9mm and often hard to find.
In the auto-loading center fire category I currently only have two calibers, .380 ACP and 9mm. Sold my 40 S&W and never owned a .45 ACP.
Old Design Firearms:
Yes the PPK is an old design. The PP was released in 1929 and the PPK in 1931.
Browning Hi-Power. Browning built two different prototypes for the project in Utah and filed the patent for this pistol in the United States on June 28, 1923 and granted on February 22, 1927.
Model 1911. The M1911 pistol originated in the late 1890s.Among the areas of success for the Colt was a test at the end of 1910 attended by its designer, John Browning. 6,000 rounds were fired from a single pistol over the course of two days. When the gun began to grow hot, it was simply immersed in water to cool it.
(Info from Wikipedia)
The argument that there are modern designs that are better needs more backing, references, and data showing this to be the case. Also, on these modern weapons, how often do they advertise that they are based or use some aspect of a design from John M. Browning?
Of the top of my head these are my requirements for a firearm:
Must haves:
Accuracy. One shoots to hit a target.
Precise. The groupings should be extremely tight and the pattern of the group should be evenly distributed.
Reliable. When the firearm is clean and maintained it should fire every time (unless the ammo is at fault).
These must haves out weigh any other factors in my opinion.
Like to have:
Good fit in hand.
Snag free sights.
13+ capacity.
Nice finish.
Easy break down / field strip.
This list could get long...
I would rather have a pistol that doesn't feel the best in my hand but shoots grapes at 10 yards over one that has new nifty feeling grips, radioactive glowing sights, 17 round mags, rust resistant polymers (that is a pun), blah blah blah.
Also I find the excuses made for "popular" brands are starting to sound like descriptions of the Emperor's new clothes. On rare occasion should a firearm that enjoys the reputation of "quality" need to go back to the factory. If it does then it is not quality and the reputation is not founded. In my opinion, because I have fallen for this as well, top tier priced firearms are exclusive and it is a status symbol to own one, and with that it must be of quality because of its cost and I must defend my purchase. Anyone saying it is not quality becomes a personal attack on my rationale.
In my opinion, a top tier firearm should work out of the box. There should be a test target and the spent brass included. Lengthy break in periods are excuses. Sights might need adjusting but they shouldn't always need adjusting for everyone. Customers defending a product because "it is made by humans and is mass produced" are just obvious statements and bring nothing to the table. Recently I have a theory about the quality issues so often reported. I am starting to believe that manufacturers are counting on the average gun owner to buy the gun, shoot a box of ammo through it, and put it on the night stand and never shoot it again. Statistically that might be the normal use of most pistols sold. If so, then they will never know that at 200 rounds the extractor gives out, or the metal in the slide is too soft, or the sights will fall off.
I have ranted a bit.
Walther PPK/S is a solid design, accurate, and precise. It shoots .380 and other smaller calibers. A .380 is a .380 and nothing more. The PPK is flat and doesn't print much. There have been several complaints of not feeding and polishing the feed ramp. Mine has had no such issues. An auto-loading weapon is all about timing, weights, spring strengths, etc, and in my opinion the old designs have it right. In my opinion, miniaturized versions of old designs often suffer from timing issues. Rent one and shoot it if you can. If you can not get the best deal on price as possible in case you don't like it and have to sell it.