1. Platform. Its not about 1 canonical interface or usage. Its real time social information network plumbing. Build your own idea on top of it. In the beginning it will be twitter clones, eventually it will be hooked into all sorts of information generators and consumers in different contexts.
2. Its about incentives. The incentives are for app.net to build the apis to support things twitter of fb never would, due an incentive to drive innovation, not stifle it.
3. Its about users control and choice. Use the interface or apps you want. Control where your information goes and who is mining it.
4. Its about friction. There is friction to blatant abuse via a pay model and there is a lack of friction to develop frictionless sharing with things like instagram.
5. Its about ownership. Your data is yours unless you choose to give it away to others.
6. Its also about alternatives to a single model for success (winner take all ad based strategies). I think its a mistake to think that its only successful with huge network effects. The infrastructure can service uses and apps that export information to other networks as well as in network uses. Its successful if it has paying users that pay for opex and capex and generate some profit.
The counter to this is that its difficult to explain to grandma in omaha until the new apps and usage models get built. If its just a paid twitter, it will fail in its ambitions. If it leads to safe private frictionless sharing in ways that couldnt realistically be contemplated before, its a success. The alpha proof of concept that is in place now is twitterish, no denying, but people are already working on things that just arent possible with facebook and twitter today.