Prior to moving to Higer Logic, we had our association on the platform that came with our AMS system. Unfortuantely, despite the promise that the AMS could provide everything, the community development UI was something to be desired. Since our community is very robust and needed a place to thrive, we looked into Higher Logic as a community discussion platform. We use it not only as a forum, but also a place where committees and our Board can interact. The API integration was very smooth, and from a user perspective, our members love it. They get to choose how they recieve information and update their own profiles. Better yet, our committees can all go to one place to get all of their documents and information.
From an administrative perspectie, my only frustration is that if you change information in your HL profile, it does not connect back to the database profile. The result is that some members think they have changed information with us and they have not. However, I realize there is no such thing as a platform that does everything, and this is the only downside I've seen thus far. Also, from a reporting perspective, you really have to use the users group sometimes to help ifgure out where your needed report is. The reporting functionality is pretty robust, and as a result it can sometimes be hard to find things.
Overall, I would highly recommend HL to any organization that is looking for a robust platform for community development. I haven't been able to find a platform that can come close to its overall funcationality.