SAP can sell, for sure.
It's just that there is not a single SAP system anywhere in the world that is fully implemented.
SAP sells a shell that its consultants must charge by the hour to customize.
True about SAP. We've run Oracle ERP for the last 4 years. It works fine, if a bit complex to setup (since it is suited for a wide variety of businesses). The database and application servers only go offline when I tell them to.
What you see as a drawback, I see as the selling point. Sure SAP is always in some sort of development mode, but this adds to the 'robustness' of the tool to meet ongoing business demands. I was an SAP consultant, now I work for a company that wanted to buid a core-competancy within their IS. :)