[kermatt]

VBA, which was removed in Excel 2008 and returned in Excel 2011, is not fully compatible with Windows versions, where most users author code.

Backend data connectivity options are virtually non-existant. Excel 2011 has what appears to be a 10+ year old version of MS Query.

Some 3rd party financial plugins are Windows dependent, and I believe some of the Microsoft analysis additions are as well.

[omni]

You nailed it. I would use less generous language than you did to describe VBA's deficiencies in Mac Excel 2011. Huge parts of what could be considered the stdlib are totally missing in the Mac version. The language doesn't even have native dictionaries.

[bsg75]

I doubt MS wants Mac Office to be on feature parity, otherwise there is one less reason for businesses to keep buying Windows.