This is a good tire to balance street and dirt riding. I haven't tried it on dirt, but the knobs look decent for digging into loose over hard or getting over wet rocks and roots. I wouldn't suggest these as a off-road only tire, as the center knobs don't have gaps for grabbing rock/roots. I don't think these would shed mud well either.
On the road, they roll relatively fast and don't make a lot of noise. The rubber compound is softer than a standard road tire, so you will get above average grip, especially on uneven surfaces and poorly maintained roads.
I do a combination of dirt and street and this tire fits the bill. Handles nicely in the dirt and while a little lumpy on the street, it has plenty of grip. I really like the look it adds to my bike.