One early criticism (aside from the sharing bugaboo) is the header is larger making the allowable reading area much smaller.
the topmost the feed content can be read is ~193px from the top of the browser. And you can't scroll down because of the way the page it built.
Here is what firebug told me:
29px - account bar
59px - search bar
73px - feed toolbar
32px - feed title bar (in the reading pane)