Great for eradicating smaller critters outside of 22 LR range. Most are more accurate than a 22 win mag, so you can get a little more range than with with a 22 mag.
Up close they blow up small critters, so I don't like mine for squirrel or rabbit hunting. I mostly used mine to dispatch prairie dogs out to 175 yards. I could hit them further, but the wind is hell on that little round.
Within a relatively close distance, I think they do fine dispatching larger varmints, but I wouldn't want to shoot bigger varmints past a hundred yards. I don't want to wound critters, even varmints.