Now that version 1.1.1 is out, I wanted to update my earlier review of Kiwi now that I have had a chance to really try the application out and engage/pester Isaiah, the developer.
Kiwi is on the fast track to giving Loren and atebits a real run for their money for best Mac Twitter application. A number of bugs have been worked out in a relatively short period of time, which speaks to the commitment and skill of the developer. Plus, having a solid partner in Elixir Graphics creating terrific themes and graphics for the application is a major plus.
As of right now, Kiwi is better than Tweetie. Hands down. Excepting the soon-to-be addressed Oauth issues (Twitter lists, proper app attribution for user posts, etc.), Kiwi has all the modern features power users expect from their application of choice. And I don't need to go again into the power features like rules, customizable lists, and themes. Oh, and if you didn't notice, they dropped the asking price $5 to a very reasonable $9.95. Sufficed to say, I was sold when they did that after teetering on the purchasing edge.
Overall, Kiwi is an application that is already a leading contender, and has shown me that it will rapidly improve while other big names like Twitterrific and Tweetie stagnate in development limbo. I highly recommend it, as it is only another release or two away from being a true five-star application.