Talk to any power Excel user and they'll tell you differently. Those users never even touch the mouse, all they use are keyboard shortcuts. These shortcuts don't translate over to the Mac version of Excel.

Conditional formatting support is also limited as well as any macros that were programmed don't always work on the Mac side.

Finally, pivot tables just don't work well on a Mac. When people are analyzing a huge spreadsheet, the Mac just doesn't seem to know what to do.

If anyone is a power Excel user, it's highly recommend you install VMWare/Parallels/Bootcamp and use the Windows version.