Well integrated to Joomla!, it allows to use the same logical structure for commenting and permissions plus the possibility to embed tags activating or inhibiting the comment function for particular articles.
I see two (potential) flaws in JComments
1- If your visitor has access to an article but is not allowed to comment it, he will get an invitation to comment and then be told he is not allowed to do it. I would prefer not to offer a non available option.
2- When a particular comment is about many articles from the same screen, you might think of inviting comments with the end of the last articles. Accepting that invitation, the visitor will be redirected to a "fresh" screen bearing only that last article inviting for comments. So he will comment on something he does not see anymore.
I suppose there is ways to work around those, but I was not able to contact JoomlaTune's forum or any other knowledgeable instance about it. I do not think this lack of responsiveness characterizes JoomlaTune, might just be a temporary glitch in their systems.