ROSA Enterprise Linux Server with its initial "Helium" release is based upon the Red Hat Enterprise Linux 6 package-set. The product page for RELS also says its based upon server solutions from Mandriva in addition to Red Hat.
The product page for RELS describes its advantages as having centralized account management, web-based administration interfaces, high scalability, and support for Windows and Linux clients. The key features are a user-friendly GUI with web-based administration tools, single sign-on support, easy integration within existing corporate networks, and detailed documentation.
ROSA Enterprise Linux Server is using LXDE as its default desktop environment, but GNOME 2.28 and KDE 4.3.5 packages are also available. Upon initial examination it doesn't appear that RELS is too different from Red Hat Enterprise Linux offerings or the other RHEL derivatives like CentOS and Scientific Linux.
ISOs are available while it seems ROSA will attempt to offer their Linux-based OS under a support licensing model. ROSA also offers a KDE-based desktop Linux distribution and products for Internet TV, In-Vehicle Infotainment, and Classrooms.