About a year ago I joined App.net amidst a number of changes to Twitter that I considered to be detrimental to the service (and still do). App-dot-net or 'ADN' promised all the features of Twitter and quickly delivered and then surpassed expectations, but features are only part of the equation. Now I don't feel that ADN managed to reach the critical mass of users required to get close to Twitter's usefulness — something attributable almost entirely to it's community.
So a year on, while I still think ADN's objectives are laudable; their service isn't terribly useful to me and for it's faults Twitter remains valuable thanks to my friends and acquaintances in spite of Twitter's own changes. So the apps are uninstalled and pretty soon my account will downgrade. I made some good friends there that I will keep in touch with by other means, though I'm a little sad it didn't come to more for me.