I must admit that I have never understood the growing popularity of the social commenting systems. Having comments hosted on someone else's server where they could be lost forever has never appealed to me. Disqus recently added importing and exporting of comments to address the issue. It seems coComment is still hosting your comments for you in spite of a recent backlash by blog owners requesting comment ownership .
After checking out the beta site for coComment's face lift, I was left with mixed feelings. Is it a better service than it was before? Yes, absolutely. The new and improved coComment offers many more social tracking features, social networking features and personalization options like a profile page. The company has also teamed up with retaggr to give you a way to make a "comment business card" you can use to draw other people toward your comments in coComment.
A plus for the sidebar feature is having a way to follow comments in coComment in real time as you move around the Internet. I'd rather have this feature as something I could integrate into an existing toolbar, personally, but overall it is a nice feature. It just takes up a lot of room on my laptop screen as a sidebar, and makes it harder to follow my tabs.
Speaking of tabs, I am an avid Tab Mix Plus Dev Beta and FireFox 3.x for Mac user, who often has over 200 tabs open as I research articles and generally try things out. coComment's beta did not play well with Tab Mix Plus or Colorful Tabs. Having the sidebar open caused some serious lag time and several freezes. Turning off Tab Mix Plus and Colorful Tabs seemed to help, but that is a deal breaker for me - any new toy has to work with the old toys as well or I can't justify using it.
In the end I think coComment has made strides in the right direction. Adding rankings, groups, tags, profile pages, portable comment cards, notification via your MycoComment page and ways to explore the comments of others are all good things. Even so, the buggy behavior with my existing plug-ins is a deal breaker for me, and using any of these social comment services is something I do sparingly.