It's a pretty poor example. I'll try and put some others up.
But look at 'sebastianmarshall.com' on line 4 - it's so much more compressed. In fact, before it is 139px wide, with acceleration it is only 132px wide: it's not just the look, it's actually changing the dimensions of the text!
I added the white lines in Photoshop - with acceleration on, the "Reports in September 2010" gets both narrower AND bolder, resulting in a very squished, very ugly presentation. The calendar headers are likewise far less clear.
http://i.imgur.com/gVFYk.png is from Basecamp - note the vast difference in navigation width, and the width of the "Comment" in the blue box.
http://i.imgur.com/LgGOJ.png is the Basecamp nav item blown up - the box on top is accelerated. It's thicker, more narrow, and it's got all those crazy colored artifacts.
