Pretty good. Obviously not as good say a vet bring back K98. Expect electro-pencil forced matching by the russians and shellaced stocks. There may also be various capture markings on the reciever and some proof marks may be marked out. Functionally they are great!
Also, even though they are not the Crème de la crème they still are worth over 400 USD. Drill/Tapping the receiver or hacking the stock will result in significant decrease in value.
Actually I have never seen an authentic PPSH-41 for sale. In the United States, they (fully automatic firearms) have to be made and registered before 1984 to be purchased legally. Consequnecy, such arms are very expensive and hard to get. Heck, some transferable machine guns cost more than a Mercedes.
The PPSH-41 is made new today in semi-automatic only with a real nasty looking 16" barrel to meet federal SBR laws.