Reporting Services

We're looking at using SQLServer Reporting Services for our general
reporting requiremets. We have a mixed DBMS environment of which
SQLServer is important but is not the main DBMS. From a review of SSRS
it seems like a very useful way to present a coherant user interface for
reports using disperate data stores as it can use ODBC as a data source.
However, I have been warned by our developers that there are
limitations in SSRS in terms of the features available when accessing
data via ODBC rather than accessing SQLServer (or perhaps using OLEDB -
I'm not sure which).

Could anyone point me in the direction of usful documentation covering
this aspect of SSRS or give me the benefit of their knowledge.

Thanks in advance

Laurence