I think its is better to have a comments box on your hub.
Firstly, Internet users love to interact and that can help build trust between writers and readers.
Also, I believe the comments act as more fresh content for the page. This is what the search engines like to see and they reward it by putting your page on a higher search results page.
The comments should continue the theme of the hub and add further value to the reader who finds the it on the engines, etc.
Comments like "great hub" add no value to the reader. Maybe comments like that can be put in the fan mail.