A recessed cylinder means that material has been removed around the rear opening of each of the cylinder bores so that the rims of the cartridges drop in flush with the surface of the back of the cylinder. The cartridge rims are "recessed" into the rear face of the cylinder. A non-recessed cylinder just has the cylinder bore holes drilled in it and when the cartridges are inserted the entire rim of the cartridge remains exposed. Only magnums and rimfires (22LR, 22mag, 17HMR) ever had recessed cylinders. Rimfires still do.
Pinned refers to the barrel. Prior to 1980 a hole was drilled through the frame on the top side of the barrel, just where the barrel threads screw into the frame, and a pin was driven through the hole. You can see the ends of the pin on both sides of the gun just above the bore of the barrel. The pin actually engaged the threads of both the frame and the barrel, and it prevented the barrel from unscrewing out of the frame.
In answer to the Gunhohulk's original question: I have a 65-5 that isn't pinned or recessed, but it is such a sweet revolver that if I had to get rid of all my guns it would be the last one to go. About as close to revolver perfection as it is humanly possible to achieve. I paid $450 for it 3 years ago and prices have done nothing but rise significantly since. If I were buying it today I wouldn't flinch at all at a price of $600 and would probably be willing to pay up to $700 for a really nice one.