Microsoft recently published a whitepaper that provides guidelines on the Dynamic Management Views that are available in SQL Azure, and how they can be used for troubleshooting purposes.
Quoted from the document:
SQL Server generates an optimized query plan for all the queries that are executed. This allows the SQL Server optimizer to reuse the query plan when the same or similar query is executed to retrieve the data in the fastest time possible. As the data and the statistics on that data change, the query plans become out of date and can become inefficient. It is important to identify these queries and tune them for optimal performance of the application and consistent user experience. The DMVs just discussed directly help in identifying the problematic queries
Download the whitepaper: Troubleshooting and Optimizing Queries with SQL Azure