We buy Volume License and then downgrade and use Office 2003 for our users as well.

We had a couple more advanced users try it and they did not like 2007 either because of layout changes. Also in my opinion probably less than 10% of Office users in the World even use half the features and power of Office 2003. So aside from some "neat" features and an expensive price tag I don't see too many mission critical reasons for upgrading to Office 2007 aside from keeping Microsoft in business.