I had a remarkably different experience upon opening the app. Much like with the App Store itself, the head-scratching UI left me bewildered and confused more than once.
Twitter for iPhone follows this model to a tee: accounts, tweets, tweet details — arranged left to right, with animation as you move between them. In today’s new Twitter for Mac, though, the sliding animations when you switch between tabs add nothing contextually. They’re not merely harmless eye candy, either. As Morgan notes, these animations create a false sense of stacking where no stack exists. They’re technically excellent, but conceptually misleading.
I think Tweetie 2.0 (a.k.a. Twitter), though great in many respects, is a bit over the line in terms of custom user interface for the sake of looking cool. Custom UI makes sense when you have a problem that the standard controls and conventions don’t solve, but too often there doesn’t seem to be any design benefit from the deviations. I like having the title bar, toolbar, and search at the top of the window. I like being able to move the cursor without stuff fading in and out beneath it. It just seems very busy. I’d like to vote with my Dock and am tempted to use Hibari, but it doesn’t support multiple accounts yet.
Update (2011-01-26): Riccardo Mori’s thoughts on the new Twitter for Mac.