Awesome work! I'm definitely using this over Google Reader from now on!
But there are few tiny details I hope will be fixed soon:
The "Original" tab is the default one - which slows down the whole thing if I open some content-heavy site, and the reason why I use feed readers in first place is not to have to watch those horrible sites at all, so it would be nice if we could change the default view.
The other thing is that there is no way to change the folder to which certain feed belongs. As well as someone before me commented, you can't delete feeds either.
The default view is the last used view for that feed. I'm planning to have that in later today.
Drag and drop moving feeds is coming sometime this Summer, but you can delete a feed right now. There is a "manage" button at the bottom of the feed bar.
I honestly have no idea where the world is headed to these days...