This is a curious web browser that, like OmniWeb, is built on Apple's WebKit. While it has its idiosyncrasies - a large tab bar for one - it does have one feature which is not replicated in any of its rival programs.
OmniWeb has visual tabs, but the Japanese developers of Shiira have managed to bolt on an Exposélike viewer onto the application. Simply hit [F8] for the contents of each tab to be displayed in its own window. And as with Exposé, selecting one window will make it active.
Another interesting development is the ability to access bookmarks from both Safari and Firefox without actually importing them. Interestingly - and this is probably to do with politics - Shiira makes changing the User Agent String (the information that websites use to identify a web browser) very easy, while Safari doesn't. The upshot of this is that you can use Shiira to access online banking services that are denied if trying to use them in Safari.
The application makes good use of Mac OS X's drawers, providing access to bookmarks, downloads and date-by-date browsing history. The interface can be styled to follow the familiar Aqua or brushed metal look. And while the default theme is pleasingly pastel, there are other themes available on the project's website to make it look more Safari-like.
The latest builds have even begun to integrate extensive RSS features, but these are currently limited to Tiger users.
Shiira's developers have said that their goal is to create a browser that is "better and more useful than Safari". On the strength of this promising early release, we can say they have a good chance of achieving it with a few tweaks and improvements.