Birds, Ducks and Robots is a look at basically how there is no "perfect" twitter client for iOS. I loved Tweetie and the official twitter app it turned into until the current version. Even ignoring the new layout ("connect", "discover", etc), it's slower and feels more memory and CPU hungry.
After Tweetie was acquired by Twitter Inc. and rebranded as Twitter for iPhone I slowly stopped enjoying the app. First it was small things like removing power user things such as TextExpander touch support. Next it was putting more focus on things relevant to Twitter's bottom line more than my use of the service: trending topics and top tweets. Next, the infamous #dickbar.
I've personally switched over to Tweetbot but it's missing some of the niceness that the official twitter app has, but does give me the light and fast feel that I expect.