I cannot depend upon Twitter as a news reader because I follow too many colourful characters. They generate noise. I can distill information manually from Google Reader on my mobile phone because I follow fewer than 1000 feeds through Google Reader. I also use FreeNews on my Nokia N97 because it gives me offline reading capability and the facilities to email items or post them to Delicious. My network on Delicious keeps me advised of things I miss when I walk away from reading feeds or listening to Twitter for days at a time.
I depend upon Twitter's search capability for recent items. In fact, most of my usage of Twitter is through searching a cluster of 12 terms, words that often change week to week. I cross-check key search term results against Feedly results, often awarding greater standing to items that received more favourite stars or more clicks on Twitter. I would not depend upon Twitter search revealing anything more than three months old, however.
If it's truly essential, it can be carried in your pocket. The real acid test of something's value is how it translates to your pocket media arsenal. Feedly won't work on S60 phones and it doesn't work on the iPhone either. However, the combinations of Feedly, Delicious, Google Reader, and FreeNews give me pocket-sized news aggregation.