Yeah it's not very known.. even in the Netherlands most people don't know it. I was surprised myself when I discovered it!
But I think the key thing is that it appears to be mostly that: surveillance. I think there's no kicking-in-doors and that kind of stuff going on. I do think the Dutch intelligence probably works closely together with the US and I've read several times when apparently some Dutch intelligence was key in aiding the US with regards to some important global issues. Maybe it's like we like to spy, but let the Americans do the actual dirty work?