Lynn, at Poet and Peasant, asks everyone how they feel about comment facilities on weblogs. Hmm..good question.
I installed YACCS in order to make it easy for people to comment on my posts. So far I have had only a handful of comments. Maybe what I write isn't interesting. Maybe people have nothing to say. I don't really solicit comments. I never say here's something interesting, tell me what you think. YACCS seems to work fairly well. I have noticed that their server has glitches that make my pages slow to load sometimes.
Now about the ability to comment on other people's site - I like it. When I'm rolling through the blog roll and I see something interesting (and I have time) I leave a comment. Sometimes I go back and read the comments after my comments to see if anyone is talking to me (or about my comment). It makes the experience more interactive. I have on occasion emailed someone who doesn't have the ability to receive comments - Lynn for example. It takes more effort so I don't do it very often. Of course if I have something private to say, I would always email rather than comment, but the whole "blog" thing is about being open, in my opinion, so commenting seems to be an integral part of the experience.
Just my $0.02 before federal, state and local taxes.