First and foremost, this is THE best question and answer forum solution available in the JED. I tried comparing this with few others but this one's far ahead out there... in fact, this extension sets the standard far higher for any joomla extension available today. I say this because, this has
+ Neat and clean front-end and back-end interfaces
+ Highly customizable to every details (developers have even given options for Akismet integration / ReCaptcha / Adsense integration / Pingomatic etc. all within its setting)
+ Integrable with common profile management systems e.g. CB, JomSocial etc.
+ Social integration options included (fb, tw, g+, digg... you name one)
+ Points/ badges
+ Notifications,e-mail (also crontab setup possible)
+ Customizable Likes, Accept this as answer (or reject) type features
+ and many many more.
Last but not the least, they have the best support people available - and I mean it. I asked them -
1. Customized feature - and they did it
2. Goofed-up something in the backend settings - and they fixed it
3. And all the responses were in an hour's time.
That's why I say, they set a pretty high standard for any Joomla extension out there.
And what if you face some issue? Or you want some customization? Or you don't understand something? I got to tell you that Alex (the developer behind the extension) is an extra-ordinary person, who has every time gone above and beyond his first-hand responsibility to help me sort the issue. The level of support I received from them, made this product even more attractive to me.
I use both JLinked and JFbc and I am quite satisfied.