I never much cared for any of RD's acting in the show; I thought he was okay in HoDS, but that's probably because he didn't have any scenes long enough to become tiresome.
I did spend some time shooting the sh!t with him at a couple of the DS gatherings, and found him quite cordial (and he didn't try to sell me anything). When I did a reading from DREAMS OF THE DARK at the 99 Fest, he actually went out and rounded up a bunch of folks to come in to hear it, which I thought was quite cool of him -- and he was very complimentary about the chapter. So my personal experiences with him were positive. But then I actually saw him on a couple of occasions show his insufferable side with some of the other stars, and given the things so many people have told me, I can quite understand the widespread negative sentiment. It's a shame he's alienated so many people, since he's obviously capable of being pleasant, articulate, and supportive.