The latest version of SQL Books Online details the features of Reporting Services that are available in Sharepoint Integration mode and, more importantly, the features that aren't!! Be careful if you plan to migrate as there are some surprising omissions:
URL addressing is different in SharePoint integrated mode. SharePoint URLs are used to reference reports, report models, shared data sources, and resources. The report server folder hierarchy is not used. (This basically means no querystring parameters!!!)
Reporting Services custom security extensions cannot be deployed or used on the report server. The report server includes a special-purpose security extension that is used whenever you configure a report server to run in SharePoint integrated mode. This security extension is an internal component, and it is required for integrated operations.
Report Manager or Management Studio cannot be used to manage a report server instance that is configured for SharePoint integration.
Data-driven subscriptions are not available. This applies to all editions.
The rs.exe command line utility is not supported. The utility does not support the SOAP endpoint used for programmatic access to a report server that runs in SharePoint integrated mode.
Linked reports are not supported.
My Reports is not supported.
Job management features that allow you to stop a long-running report process are not supported.
Batching methods will not be supported.
I haven't tested it yet but I have a feeling this might mean that the PerformancePoint Planning operational reports may not work in this mode
The online (!) Books Online article is here