With the release of Twitter as a universal app that now includes iPad support (read the official announcement here) I feel confident that the reports of the death of 3rd party Twitter applications have been greatly exaggerated.
The UI for Twitter for iPad is, without question, unlike any other Twitter application that we've seen. Opinions around the TUAW offices differ on whether this difference is "awesome" or "an abomination." I definitely range towards the latter end of the scale, and judging by most of the comments of people that I follow on Twitter, the initial reaction is definitely one of "too busy" and "over designed."
This is in sharp contrast to Twitterrific, which just released a major update for the iPad and iPhone where the Iconfactory made dramatic simplifications to the app, while retaining the most important features for the most users. (Craig Hockenberry talked about those changes here.)
In the interest of full disclosure, Twitterrific for Mac was my first Twitter client, and I've purchased the app for iPhone and iPad as well. I even have a T-shirt and Ollie figure. You could say that I'm a big fan, but I'm a fan who has voted with his wallet.
But you know what my having-slept-on-it reaction is to the Twitter for iPad changes? "Good for them." I'm thrilled that the Twitter team has decided to push the UI envelope and try something completely different. No, it doesn't suit my tastes, but there are going to be loads of people who use it because it's free and the official app. I suspect they're going to get a ton of feedback on it. They may have more freedom and flexibility to experiment than any other Twitter app developer.Oh, one last thing, Twitter: I do think it's lousy that you have included features in your app which aren't available to third parties, such as account creation. That seems unfair, and I hope it will be corrected soon.