Based on the people I follow, I get exposed to a lot of news and ideas I might have otherwise missed, but I don't need or want Twitter to be the place where I dig in for more details. I'm fine clicking a link or Googling something if I think it's interesting enough to warrant further investigation.
I guess my main concern is that if Twitter tries to be all things to all people it's going to lose its special utility as a discovery engine. In other words, I don't want Twitter to become Facebook or a glorified RSS reader. For me, Twitter is the best source for breaking news and ideas ignored by mainstream media, sprinkled with tidbits from friends I know IRL.
In general, I'm happy with what it is now, perhaps with some better controls for blocking and preventing abuse. If they can find a way to keep the concise sharing/discovery aspect while integrating longer content, I'm cool with that – albeit a bit skeptical.
Doesn't that lead to a tendency for low quality content (content that can be consumed in a few seconds, like animated gifs, quotes, etc)? I usually want to read in-depth articles and editorials, or thoughtful comment threads.