Echofon for Mac is no longer in development. TUAW's Twitter Client Project surveys popular desktop alternatives in highly subjective reviews.
The YoruFukurou Twitter client (Free) has been designed by geeks for geeks. Packed with customizable features, it bears all the hallmarks of design-by-engineer.
Anyone searching for precise end-user control will gladly find options for many display and notification tweaks. You can set up multiple Twitter accounts, control keyword highlighting and much more.
What the app doesn't deliver, in my opinion, is a sophisticated design aesthetic, either in usability or the visual layout. Although it's blessed by one of the cutest icons possible, that same quality of visuals hasn't transferred to the app itself. I found the app window cluttered, confusing and lacking in refinement. I was put off by many of the app's default design choices, such as highlighting mentions in red.
It takes a tremendous amount of effort to simplify an app, polishing it to the point where features are obvious and follow the user's desires. YoruFukurou isn't one of those apps.
It's got most of the features you expect in a Twittter client but the flow in scanning, reading, replying and following conversations left me unimpressed. It took me forever to discover how to view conversations (Conversations icon in the primary toolbar, Timeline > Conversations, or Command-3), an approach I felt was unintuitive. I had expected conversation choices to be tied to individual tweets, not to be placed among global modes.
I committed to testing YoruFukurou for an entire week. During that time, I often found myself Googling to figure out how to do one thing or another. This is not the hallmark of fine design. I got through the week and I was able to use the app, but I kept sneaking back to Echofon to get the "real work" done.
On the plus side, I did appreciate the app's many features. From translation to shortening links to a built-in error console, the app is packed to the gills with options that will please demanding users.
The app was reliable, and seems to be built on a solid foundation. I did not experience crashing or flakiness.
From what I can tell, YoruFukurou has a loyal fanbase and remains in active development. You can follow the development team at @aki and @hydroxygenic on Twitter.