Views are a valuable tool for the SQL Server Developer, because they hide complexity and allow for a readable style of SQL expression. They aren't there for reasons of performance, and so indexed views are designed to remedy this shortcoming. They're great in certain circumstances but they represent a trade-off, and they come with considerable 'small print'. Jes Borland explains.
Here is some information about an important MERGE “wrong results” bug, involving indexed views, that could be affecting the accuracy of your queries right now, and what options you have for working around the problem.