Exporting from SSRS to EXCEL is not as seamless as one would hope.  I’ve run into a few issues that have been spicing up my life.

1. The EXCEL renderer has a footer limitation of 255 characters.  So any nifty footer on the report with instructions and such most likely will not get exported.
2. Some web safe colors don’t export properly.  For instance Pink (#FFCCFF) exports as Yellow (#FFFFCC).
3. In some cases tables and textboxes don’t play nice and even when sized to the same size through properties EXCEL will throw in an extra zero-lengthed column or three.  Fortunately this little goodness is a always favorite to the end-user.

Oh, well… can’t win them all.