...please only speak from direct experience. (Score 1)

I think most of the people commenting here have no experience on the leadership side of a large, complex software project (from either side of the table, consultant or customer). Let alone, what's involved in an RFP or vendor/consultant selection process (again, from either side).

A project like this will stress the capabilities of even the most competent management and execution teams, and are simply beyond the capabilities of any one person (yes, even the armchair experts posting here).

Technology is rarely the issue (these problems get solved). Things like the internal politics and culture are among the real problems - they are hard to manage, and are always unique in each organization.

To boil this down to "SAP Sucks" or "Consultants Suck" is ridiculous and unhelpful.