I am knocking off a star because there seem to be no way to know if an update was posted beside going to the dev website, downloading the package and checking the version inside. I wish it would integrate in Joomla extension update mechanism.
What I also truly appreciated is that, while I am no programmer, I suspect CB API is really easy to use because of the amount of extensions that provide a plugin to integrate to CB profiles. CB itself is also pretty stable. I can't speak for 2.0 since it's been out for only a few weeks, but v1.9.1 ran without a hitch without problem.
And finally, the support. I got nothing but praise for it. While sometime I didn't like the answer(like: "This will be fixed in CB 2.0" which was months away back then) they have ALWAYS answered within 24 hours on their forums. The memberships price are not cheap(but you can get the basic extension itself for free), but I am glad I took one as a "thank you" for this great extension. It is unique in it's field right now, and v2.0 fixed the only small annoying things I had to say about it(the registration form and login box were not responsive so it would not display correctly on a tablet or phone. All fixed now). 5 stars
If you go on their support forum you will see tons of posts about this, and absolutely no answer. It seems the developer is gone.
Now, there is no way I can keep up with new hacks so I tried and installed RSfirewall. Since then, zero successful attack! And I love that it runs a full security diag on the website and tells you what to change/fix. Great support also from the devs when I updated the website to Joomla 2.5. Five stars, although I wish the functionality was built-in joomla. I learned the hard way that a default joomla install it NOT secure and that there are alot of stuff to do to iron it.