Yes, the Jupiter 9 is an amazing miracle of German engineering "acquired" by the Soviets during WWII and put to wonderful use.
This is one of those lenses that has such a distinct quality to the bokeh (in no small part to the 16-bladed aperture) that I can
almost identify photos taken with this lens on sight.
Granted, it's not the world's most practical lens on a modern Pentax camera, but it's still a great piece of glass.
I don't use my Jupiter 9 as much now that I have the DA 70mm f/2.4 Limited. I also have a friend who can lend me a 77 Limited when I need it, but I find the 70 handles everything I used to use the Jupiter 9 for on a regular basis.
Here's a snapshot I took with my very old, early production Jupiter 9 a while back:
The only thing you have to watch out for with the Jupiter 9 lenses is that many have less-than stellar Soviet-era workmanship and most of the older lenses have failed at some point and either been disassembled and put back together or they're being sold on ebay while they're still broken.
My particular Jupiter 9 shows tell-tale common signs of amateur repair work (oily aperture blades and a reversed aperture dial). However, it still produces great photos and I paid next to nothing for it.