The service looks very simple to use and extremely cute. All images are shiny and well designed and installation and usage are very simple. That’s the good news.
The bad news is that contrary to Twitter the chat is extremely fragmented. Competitors to Twitter never take off because everybody keeps coming back to Twitter. Firef.ly is everywhere an might as well be nowhere.
Then there is the debatable value of the comments. It is a problem that affects a lot of annotation, (DISCLOSURE: I started Fleck.com, another annotation service) chat and comment services. Given the chance to say something it often turns out that most people don’t actually have anything to say. As you can see in the screenshot a typical Firef.ly enriched site generates a bit of uninteresting buzz on a page but hardly any meaningful conversation.
That doesn’t mean the whole service is useless though. If you have a site with a large userbase and tight community it might be interesting to see what happens if you add Firef.ly to your website. Give it a try and let us know how it works for you.