Marco Arment breaks it down:
In many ways, we’re better off now: publishing online is far easier, less time-consuming, and more accessible than it has ever been, which has brought content, voices, and consumers online that wouldn’t have been otherwise.
But all of these proprietary networks that want to own and hold in your content are reversing much of the web’s progress in some other areas, such as the durability and quality of online identity.
This is why I prefer people write on Tumblr, or Posterous, or Wordpress.com rather than on Facebook or some other walled garden. And if you’re going to be on one of those sites, be sure to grab your own domain.
Related: The Fred Wilson school of blogging. I don’t have a blogging strategy, but I do have online habits, and Fred’s mirror mine pretty closely.