I find the current icon distracting. For one thing, the fact that it is the default notebook doesn't really matter to me, so I don't need to see that constant reminder. Plus, I half consciously associate it with "downloading" something, since the icon is off a down arrow into a box. So I always have this nagging feeling that I'm waiting for something to finish downloading. I'd rather have it as a simple * symbol or something like that, or just not have an icon at all. Would be nice to have the option to hide the icon.
Anyone else find it distracting?