You can still use the dropdown menus to get to deeper levels, though (and that's done on hover, not click, though it isn't the standard SMF menu!) so if you know precisely where you want to go, maybe it is quicker that way, but even with this front page it has certainly encouraged a wider reorganisation of items.
The admin panel show how the sidebar can be useful (you don't actually have to visit the homepage again to view all of these details from within an admin area.) Oh, I did the redesign for the fieldset, too. I felt I had to do it because Pete is so much in love with fieldsets and likes using them everywhere. Now with good reason :D (This is all part of the 'work in progress', as we have yet to see whether we'll use fieldsets a lot or just on the odd page.)