I guess one's experience of yoga classes is very subjective for every student.
But having said that, I found Karen's teaching to be helpful and attentive - and in the end transformative. I think that some yoga students misperceive the Iyengar "method" as being too strict, which might account for some people's reactions. My own take is that through learning certain very specific actions and awareness, one can develop "less" constriction in one's body and mind.
I loved it - the facility is nice in a simple way. The real deal, not McYoga.