I think if you tone down the shadows, the rounded corners won’t be as visible.
OK!... OK!... I’m going to reduce the rounded corners…. You people are so straight and edgy… I like mine soft and smooth…
If you let me, I’ll try to explain what’s with all the rounded corners in terms of usability and user psychology.
Rounded corners define boundaries, completeness of the object. When you use too much of them, well… to much boundaries = no boundaries (they loose their meaning, as if you use h1-size for all body text) = mess in the user’s perception. A good solution to reduce them without loosing too much of the current style would be to use them to group similar objects (groups), and not to emphasize a single one.
One more usability problem I spotted – the thumbnail tooltips on the right are too delayed. There will be too few users that will wait so long for the tooltip to appear. I found them accidentally by leaving my mouse over them to go for a glass of water.