This is a good benchmark for stressing rendering, layout, and style. We should be testing the real frameworks being used on the web and Speedometer is as good as any I have seen. Unlike IE's testdrive, Speedometer's source does not look like it was written by cherry picking examples that perform well in a specific browser.

I'm skeptical of a minor point though: synthetic events do not accurately simulate end-user responsiveness, especially when it comes to frame and event scheduling that occurs in a different process. There's a difference between simulated and real events even on the renderer side (see: http://trac.webkit.org/changeset/164871).