I got these to use in my new Marlin XT-22 bolt action (22" barrel, 1:16 twist rate). Just shot about 80 rounds in my backyard, trying to hit soda cans, cardboard boxes and other random objects at 15 and 25 yards. My comments:
1) Noise was comparable to an airgun. Obviously recoil was nonexistent. Very pleasant to shoot without ear protection! We have double windows and my wife could barely hear the noise from inside the house about 30 yards away from the point where I was shooting (not aiming at the house!).
2) As far as I could tell by the shape of holes, no tumbling (of course, distances were relatively short).
3) I had cleaned and oiled the rifle before and decided to cleaned it again after, just to see whether the black coat had left anything dirty. Everything was very clean, it looks like you could go 1,000 rounds before getting any appreciable residue. I did not notice any of the "sand-like grit" described in the other review, but then I had a lot more barrel to spread that out. It was late in the evening so I had to limit my activity to 80 rounds, but next time I will make sure I start earlier!!!
4) Penetration was good. Bullets went through a few layers of material including a sturdy old faux leather-covered notebook and could not recover any (although I still have a box filled with some old software and manuals that I still have to open: it made a funny "springy" noise when hit. Must have been CDs!).
5) All rounds worked perfectly, even as I was breaking in a new rifle (which, by the way, is awesome!). As for precision, not much of a clue (with smaller targets it was hard to know they had been hit until I went to check, and I was not too worried). But my guess is they more accurate than the shooter!
6) I think I remember reading some reviews elsewhere complaining about the smell (not sure if the same product though). Smell was slightly metallic, quite normal and not unpleasant.