So much support, so little time...
One of the most depressing aspects of doing your own tech support is the constant barrage of negative feedback. If you are a conscientious developer who takes pride in their work, all the complaints coming in can be very disheartening. Some developers try to balance this out by offering forums for their support. That way, the thinking goes, your users can band together, more advanced users can help each other, and while you are doing actual development work on the program, easy questions will already have been answered, and you can focus on answering the real tough ones.
We've seen this work just fine for many programs. Not only did it encourage development of a community of users and a whole third-party ecosystem, but all the talk and content also offered more google results and thus improved discoverability of a product.
However, that was mainly for products that are frequently used and whose use includes constant problem-solving and optimization. Products used by people who constantly use them to create content. Development environments have a large user community, even though the total number of developers among Mac users is comparatively small. iMovie and Keynote users band together to discuss ways to best take advantage of certain features in their presentations.
On the other hand, applications that are mainly used for consumption have been burned by forums: As most users are perfectly happily using the application and don't need to figure anything out, thousands of happy users have no reason to go anywhere and connect to other users. The only people left to seek out the forums are a few hardcore fans (great people, but sadly always a minority), and people actually having a problem.
Statistics tells us that this severely skews the forum population towards unhappy people. Looks like we're back in the same place as with support, right?
Sadly, that's not the case. Your support happens quietly, behind the scenes, one at a time. Nobody ever sees the constant stream of unhappy users made happy by help. The Forum, on the other hand, is indexed by Google, remember?
So not only is the group of people in there skewed towards negativity, but your search results on google are now, as well. Instead of seeing your web site and a few positive reviews, someone googling for your program will be inundated by complaints about every little thing that has ever gone wrong for someone with your program. They'll think that your program is very buggy, because she doesn't get any such complaints about other programs.
In the eye of the public
But that's not all: Customers coming to your forum with a small problem may see a post from two years ago that sounds just like the problem they have, and think badly of you: This problem has been reported 2 years ago, and it still isn't fixed? What a slow developer!
Never mind that the technical and social reasons for this issue are completely different, and the issue happened for one day two years ago, and the one they have is brand new as of two hours ago...
So Forums are Evil?
Certainly not. I have enjoyed the thoughtful conversations and clever solutions on many forums over the years, and I wouldn't want to miss those times and everything I learned in the process. But I wanted to sensitize you to the downsides. Look at your application, and consider whether it does anything that would benefit from having a group of users connect their brains. Is it used frequently enough by a large group of people, and is the subject matter complex enough to make a forum worthwhile?
But hey, when in doubt, just try it. But watch for the signals, and be ready to scratch the whole thing if it doesn't work out well.