The PPK/S is basically a PPK slide on a modified PP frame. The grip is slightly longer than a standard PPK's, which gives you marginally better control and a slightly larger magazine capacity at the cost of more difficult concealment, though the difference is small on all counts. Since the PP series are basically all concealment guns, I'd go with the standard PPK.
IMHO, a much better option is the Kel-Tec P3AT. It's still a .380, but half the size, one-third the weight, and much less than half the price. I have one, and I love it.
Full disclosure: Kel-Tecs have a reputation for having FTF and FTE problems out of the box, but the company invariably fixes them VERY quickly and at no charge when returned for service. This seems to apply more to first-generation guns than to current manufacture. I recommend the hard-chromed model; I've heard of very few problems with those. Mine is a HC 2nd-gen model, and I've put several hundred rounds of 10 different brands and styles of ammo through it without a single malfunction of any kind.
Walthers are made like Swiss watches, and they have that James. Bond cachet--but compared to the KT they're big, heavy, and expensive. I doubt if the BG you shoot with either will know the difference.
I had an older PPK/s in 380; I didn't like it. Mine seemed to draw blood on me every time it went to the range. I believe the problem was not the gun, but the chambering... I recently picked up a stainless PPK/s in .32 and discovered the europeans were on to something there. The .32 ACP round tames the PPK/s tendency to nip and nibble at the hand that shoots it, and accuracy is stellar; the Walther PP is also a wonderful gun in .32 and they were recently imported in serious numbers. I agree that the Kel-Tec is cheaper, smaller, lighter and easier to pack in both .32 and .380. My Kel-Tec .32 is my "always" gun ( I toted a Seecamp for a while and got hooked on the silvertip in .32), but it is fun to take the Walther out and hear that James Bond theme music in my head while I plink at pop cans!
If you have large hands you will not be happy with walthers. They will slice you up. The Sig 230 will do the same thing. I have not shot a 232 but imagine it is very similar to the 230.
For me, a .380 is a pocket gun that will get some degree of abuse. I am unwilling to spend Walther/Sig $'s on a pocket gun. A reliable Kel-tek or other similar weapon would be far better for the job. I would secure a Walther in a quality holster. If I am going to holster the handgun, I am going to carry a more substantial caliber than .380.
I have one of each. The PPKs sits in my safe and the p3at in my waitband.
The Walther is sure pretty and feels good to handle.(for me)My PPKs is about 40 yrs. old, in mint shape. Thats one reason it stays in the safe.
I carried a late model, S&W made PPK/S for about a year. Its was 100% reliable and very accurate. It also concealed easily. I would still be carrying it, but decided to consolidate my pistol calibers and sold it to buy a 9mm carry gun.