Why is "chrome clone" the only thing that people ever think of?
First off, the only things that looks even remotely like Chrome are:
1. the tabs
2. the menu button
And to that I say:
1. The tabs on Australis are proper curves, nice and smooth and even just glancing at it I get a "warmer" feel from them than from Chrome's sharp angles. Also noteworthy is the fact that non-active tabs blend into the background, which when you're using it looks really nice as well. There are a few other things but meh.
2. Some people have complained about there now being a "single button menu", to which I say "What firefox are you using again?" cuz Firefox has had a single button menu for a while. And this one is special: The new menu is COMPLETELY CUSTOMIZABLE. "Items" as I shall call them (Normal Firefox buttons, Add-on buttons, etc) can be placed on the normal bars (e.g. next to the URL bar, etc) or inside the menu. The menu can be arranged any which way you want and can have as many or as few things as you want. It takes customization to a whole new level.
Unfortunately, in the process they are removing the add-on bar. I don't care because I don't use it, but in the end I think it was a good decision. There are plenty of add-ons that seem to give you an icon on the add-on bar just to be there... and this will force them to stop. Also a few other reasons.
And like I mentioned before, Australis probably has a much cleaner set of XUL than the current interface, maybe leading to performance improvements but definitely cutting down on glitches :P