This is probably the most complicated "forums" style website I have ever seen. It's incredibly disorganized. Think Atheist is another atheist Ning website, and while it is also frustrating to navigate, it is steps ahead of this one. I blame this mostly on Ning. Honestly, phpBB forums would be better than Ning.
One non-Ning issue that I constantly run into is that people post discussions in groups instead of on the main site. This means every person who wants to reply has to join the group. This also means the discussion will not show up on the main discussions page, forcing us to manually check the "My Groups" tab to see if there are any updates to our groups and then to manually check each updated group to see what happened. And even then, as far as I can tell, often nothing actually happened. (Maybe it indicates "activity" when someone joins?) Anyway, I see absolutely no reason to post discussions in groups, unless the subject matter is not allowed in the main forums. It just decreases the chances and frequency of a discussion being replied to and divides content and the community unnecessarily (of which "blogs" vs "discussions" already does a bang-up job). There have been several occasions where I wanted to reply to a discussion but realized the author posted it on a group page. Sorry, I'm not going to contribute to this mess by joining your group.
The front page is cluttered beyond reason. I don't even know why I go there anymore. I have actually AdBlocked a lot of crap that just took up room. When I visit AN now, I link to the "Forum" section and have it switched to "Discussions" view because the default "Categories" view is absolutely useless.
I spend a great deal of time reading the bottom right corner of the screen, "Latest Activity," because I often find it more convenient than checking 3, 4, even 5 separate pages and still not seeing all of the updates. So why is something so important just a tiny box in the corner? Think Atheist has definitely done some things right that AN could learn from.
Also, Think Atheist seems to have an updated text editor script, because the problem of the cursor randomly jumping to the beginning was fixed a while ago, same with the problem of quote mode getting stuck on.
Well, that's my critique. AN has a pretty decent community, but I would really like to see in the future the merging of sites like AN and Think Atheist onto a non-Ning platform that is more conducive to discussions.
I've set up a few phpBB sites. It's very simple with clear instructions, as much "plug-and-play" as it can get without having a button that says "Install phpBB" on the hosting control panel, which some hosts actually do have. I'm not saying Ning isn't easier; it may very well be, just probably not by much.