SchemaTool->dropSchema's documentation says:
Drops the database schema for the given classes.
In any way when an exception is thrown it is supressed since drop was issued for all classes of the schema and some probably just don't exist.
However, with a recent upgrade to 2.0-RC2, this doesn't work anymore. A PDO exception isn't caught if the specified table doesn't exist already.
exception 'PDOException' with message 'SQLSTATE[42S02]: Base table or view not found: 1051 Unknown table 'UserAddress'' in /usr/share/php/Doctrine/DBAL/Connection.php:577
I'm not sure if this was caused by the ORM update or if it's maybe somewhere inside DBAL, which I upgraded at the same time.