It is risky to attempt to analyze, let alone criticize, a technology you do not have firsthand experience with and (to use Polanyi's phrase) "personal knowledge" of. Unfortunately most of Melissa Wiginton's short essay on Twitter illustrates those perils, complete with the awkward generational self-consciousness that seems to be de rigeur in these sorts of critiques. But this comment on the difference between "self-expression" and "being heard" is absolutely spot on. I would add, too, that "self-expression" requires a self worth expressing, and it is very doubtful whether such a self is formed in units of 140 characters.
Andy:

Some young pastors want to posts tweets on a screen where everyone can see them during worship, I guess to connect by knowing what others are thinking. One said, “You know our generation. We want our voices heard.”
Now, I have learned a few things along the way and one is this: We all want our voices heard. But self-expression is what happens when we tweet. Being heard happens when we listen. It’s not the same thing.