Originally, I had intended on completely overhauling the editor interface for a new and unique look that not only changed what you saw, but how you interacted with the various features of an avatar to change them. Those plans have been dropped. Due to time constraints and the already delayed release, I instead decided to leave the editor much as it is now, as seen in the Transitional Beta.
But interface isn't everything. There is still a lot of work to be done under the hood.
So far, all Big N references have been removed. Additionally, the new Flash Player 10 save and load features have been implemented allowing for the editor to save and load avatar files without requiring an interaction with the server (making it easier to use on your own site or when offline). I have taken some time to do some code refactoring, but it's still very messy.
In fact a lot of what's left is cleaning up the mess. When I first started the editor, focus was put entirely on parsing the Mii character binary files as saved on a Wii remote. Providing a preview was an afterthought (and by far, the hardest and most time consuming portion). Since the preview was built around the Mii file parsing, there really isn't much wiggle-room in terms of extending the editor to do more than what's supported by the Wii. And I can't tell you how many times people have requested to add a hat, or a new hair style, or something else that is not Wii Mii-compatible. In order for the editor to be useful outside of editing Miis, that will need to change. And it is on that which I'm currently working.
Oh, and I haven't done anything new with the XML format I proposed earlier. I guess I'll have to work on that too ;)