Comments on InterSystems Cache Database Platform

We're looking at a vendor who uses the InterSystems Cache Database Platform, but our IT department has zero experience with this system. This software package will have a pivotal and mission critical roll in our organization, so I'd like some comments on what others think of this database platform.

Mainly I'm curious how easy/difficult it is to query a Cache Database, and does it use standard SQL calls like Oracle and MS SQL? What about ODBC connections into the database from Crystal, MS Access, and OLAP tools? Any other caviets (backup, maintenance, etc)?

Thanks in advance for any suggestions or comments Cache.