Copying the core aesthetics, while glaring over the details that actually make Lion look good.<p>Especially the progress bar: sure, it does look a bit like Lion's but it absolutely lacks the subtle colors and shades.
The white box shadow on the bottom of the button doesn't seem to match Lion's buttons. I think it's a little cleaner if it's removed or darkened a bit.
What is the value in aping a particular OS's look for your UI when chances are most of your users won't even be using that OS?<p>You know what other sites attempt to copy an OS's native controls? The ones displaying fake virus scans.