That's a good question. From my perspective as a user and fan of Twitter, I would say quality of discourse. That's a funny thing though because reading a tweet can be like trying to decipher a vanity license plate. Still, that's enough to communicate some pretty important stuff (like during the Arab Spring events a few years ago).

So the logical next question is how does Twitter shape how it is used? I think the answer to that is in part, let other people take care of that. In some ways, Twitter-the-platform is much more interesting that Twitter-the-product. My current favorite example is Nuzzle.

Unfortunately, Twitter is a $13 billion (and falling!) company. Investors think Twitter is Facebook Jr. and it really isn't.