The ATLAS experiment at LHC relies on databases for detector online data-taking, storage and retrieval of configurations, calibrations and alignments, post data-taking analysis, file management over the grid, job submission and management, condition data replication to remote sites. Oracle Relational Database Management System (RDBMS) has been addressing the ATLAS database requirements to a great extent for many years. Ten database clusters are currently deployed for the needs of the different applications, divided in production, integration and standby databases. The data volume, complexity and demands from the users are increasing steadily with time. Nowadays more than 20 TB of data are stored in the ATLAS production Oracle databases at CERN (not including the index overhead), but the most impressive number is the hosted 260 database schemes (for the most common case each schema is related to a dedicated client application with its own requirements). At the beginning of 2012 all ATLAS databases at CERN have been upgraded to the newest Oracle version at the time: Oracle 11g Release 2. Oracle 11g come with several key improvements compared to previous database engine versions. In this work we present our evaluation of the most relevant new features of Oracle 11g of interest for ATLAS applications and use cases. Notably we report on the performance and scalability enhancements obtained in production since the Oracle 11g deployment during Q1 2012 and we outline plans for future work in this area.