The A/T KO's are excellent in the snow, so good in fact they are snow rated like dedicated winter tires. They aren't so great after they wear down to half tread or so, but they are still better than many generic tires. They are also good in the wet, with sipes and two channels for water.
The BFG A/T KO is probably the best on/off road all-terrain in terms of looks and off-road performance that still keeps the characterstics you want in a tire to use on pavement year-round. Lots of mud tires are not just noisy, but they are not very grippy on wet pavement due to the smooth lugs, low surface area, and they aren't good in wet, slushy snow, either.
The downsides are weight, which affects gas mileage, the firm/harsh ride, which depends a lot on the size you get and the vehicle you're using it on, and the suspension you have with it, plus the fact they lose a lot of their performance when the tread gets down to about half. Still a good tire, and with all the sizes available, you can put them on just about anything.