Tweetie -- a Twitter client for Mac OS X (the 'desktop' version, as I suppose we must refer to it now) -- was released today. I use Tweetie for the iPhone, and like it so much that -- until now -- I tended to access Twitter on the iPhone rather than the Mac, even if I was sitting in front of my computer. It's difficult to define exactly what is so good about it, but the smooth behaviour, beautifully designed user interface and carefully thought-out features all conspire to make Twitter much more fun to use than it would otherwise be.
Twitter for Mac does not use quite the same design, but brings the same design sensibility, and is equally fantastic. When I started to use Twitter, I used Twitterific, but while I liked it, it niggled at me in certain ways. I then switched between a variety of Twitter clients, most of which I stopped using fairly quickly because they also didn't sit right with me in one way or another.
Twitter is such a simple and well-defined thing that you'd think it would be easy to design a good Twitter client, but it really isn't. In my opinion, a good Twitter app needs to be there instantly when you want to read tweets or post something, but stay out of your way the rest of the time. I'm with John Gruber: I think Tweetie does that wonderfully. I thought I would miss Growl notifications or beeps when new tweets arrived, but I've found that I don't. The menu bar item turns blue when something new is waiting (you can tailor what triggers the notification), which is just enough to be a notification, without distracting you. The hotkey to trigger the main window is great for quickly summoning or dismissing the window to read tweets, and I love having a separate window and hotkey for writing them. In short, I really like Tweetie, and I'm happy to have the 'Twitter Experience' I love (I can't quite believe I've just typed that) on my Mac as well as my iPhone.