I heard some stuff from Europe 72 and prior to that I hadn't given Bill K much respect, in fact, I thought he wasn't very good.
There was some absolutely blistering mind bending shit on there.
Most of his beats are broken 16ths, that interact with Jerry's soloing. The bass drum is barely heard, which is probably the result of the recordings. It's somewhat challenging to play them, it takes some concentration.
What also gets me is the flow of intensity, like a wave. It's a really live performance thing that you can't really get from these recordings. And that's also why some of their shows were not quite there, getting that groove is probably hard when things aren't very healthy. Jerry could rip paint off a building when he was on his game.
Here are a couple links with lots of good stuff.
http://www.deadlistening.com/Their FB.
https://www.facebook.com/deadlistening?fref=tshttp://archive.org/details/GratefulDead