From my experience with PerformancePoint, and how it fits with the rest of the MS Buisiness Intelligence suite, I'll offer the following:
PPS is strong in establishing standards and processes around the annual planning process. The Planning component definitely can provide benefit to small and medium sized organizations that are currently using a spreadsheet based budgeting system.
The Monitoring and Analytics component is relatively strong with the scorecard component, while the analytical component provides basic olap reporting functionalitly. However, utilizing Excel or Excel Services via a MOSS can greatly enhance the analytics surrounding a scorecard implementation.