I have been using DNN since 2007 to create and manage multiple websites. It is a powerful and comprehensive tool which enables non-developers to build highly functional web sites. It has limitations and frustrations but it has remained my "go to" platform for the past seven years. I appear to be in good company as there are
Using DNN, I can produce a modern, subscription, website in a weekend. My site will contain an elegant skin, a graphic rotator, the ability for people to register, basic social media functions, a menu that changes as different users log in, a newsletter broadcasting ability, lots of content, pop-up windows, blogs and articles. That's a lot of functionality for free and for someone who is not a professional web developer. You can see an example of such a site at agilethinking.com. This site is built on the free edition of DNN Community supplemented by both free and purchased modules.
In considering DNN, it is important to realize that there is a large community of module developers. There are many free modules available (http://dotnetnuke.codeplex.com/) and a large number of paid ones as well (http://store.dnnsoftware.com/). A bit of web research will enable you to identify the reliable and creative developers whose modules make this platform especially flexible and powerful.
In short, DNN enables you to create a professional, highly interactive site without the need to write code. You can control the look and feel through the skin you use and enhance the functionality through purchased modules.
If you are more technical there are several rapid development tools available that will allow you to create your own custom modules (for example XMod Pro ) and if you are a developer (or hire one) you can code custom modules in C# or Visual Basic.
DNN started out as an open source project but like other open source products now has commercial versions. While the company has made good on its promise to continue developing the Community edition, the support often feels haphazard and spotty. Some bugs persist for a long time.
Some open source products seem to have a more active and welcoming user community than you will find at DNN. Within the DNN community, there is a bias toward developers. If you know how to code and are comfortable with .NET and Microsoft servers you'll be fine. If you, like me, are less technical you may find that some aspects of DNN are frustrating. This is not to suggest that the hurdles are insurmountable but some things you may want to do require you to change files on the server rather than being able to manage them from within DNN.
There is help available. If you are on your own, you can subscribe to DNN Creative or DNN Hero both of which produce instructional videos on a regular basis. A company like Managed.com will install, host and provide excellent service for your DNN site, And there are many consulting companies that will help you as well for a fee.
If you are comfortable managing your own server, you will have few problems. If not, you may need to seek help if you want to do more than the basics. However, even the basics will provide you with excellent functionality,
Despite my frustrations, I have been a loyal DNN user for many years. I am not a developer and want to be able to create powerful and attractive web presences quickly and easily. DNN fills this need.
If you lack technical or web development skills, you will be fine as long as you stick to the basic platform functionality extended by free and purchased modules. You can do a lot. If you have more complex custom needs bordering on needing to create a web application, consider hiring a DNN consultant.
If any of these describe your business you should consider DNN. You have a business which requires a web presence. You are delivering content or need an eCommerce platform. You want users to be able to register and want to show different classes of users the different content. You want to empower some users to create and manage limited content. You want to be able to send out newsletters to users based on their role. You want basic social computing functionality like groups, discussions, voting, a news feed. You want blogs and articles. You want multiple languages.
I have used all of these functions and been able to do them without hiring web developers. Being able to build and manage the sites myself is a large business advantage,
If you plan to resell a product based on DNN, note that it is licensed using the MIT license which is extremely favorable and places few restrictions on you. This is unusual in the open source community.