The Walther PPK is a great gun, I own one (Interarms .380) and carried it for many years as a BUG or when I needed a non-cop looking gun. There are a couple of issues, one is that the blow back design causes a considerable amount of recoil and with its design an bit of hammer bite. Also the mags hold only 6 rounds, which is ok but, since its made of steel it ends up weighing a lot more than it should. And the initial double action trigger pull is very heavy.
With todays light weight .380's such as the Khar's and Ruger LCP you get the same capacity in a much smaller package. And althought the recoil is still there, due to the design of the gun, you don't get the hammer bite. I do understand that the newer models built in the U.S. have a longer grip tang which protects one from hammer bite but I don't have one of those and cannot comment.
Again, I love the PPK but there are a lot of other guns out there in the same caliber that have attibutes you should look into, especially since you mentioned "deep concealment" as one of your reasons for getting one.