The "Download as PDF" feature appears to generate mangled output for equation intensive pages. I have seen this problem on many Wikipedia math pages over the past year. A simple example of the issue is the PDF created for http://en.wikipedia.org/wiki/Taylor_series. I have tried to fix the output using the "Create a book" feature without success.
This feature was very nice and has worked properly in the past. Anything that could be done to fix it would be appreciated.