Rock solid distribution for servers. Straight forward, easy anaconda installation via GUI or automated installation via kickstart. A great feature is software collections which enables you to have multiple versions of packages installed and managed via the fantastic yum package manager.
Centos is rock-solid, both on the server and the desktop. The distro has very long release cycles and is relatively secure (for instance, vulnerabilities are patched quickly and the distro runs with SELinux in enforcing mode by default).
The inevitable downside is that most packages are relatively old - and they get older over time. For instance, getting Drupal 8 to run on Centos is tricky. Drupal 8 requires PHP 5.5.9 or higher but Centos 6 ships with 5.5.3 and Centos 7 with 5.4.16.
Another thing worth mentioning is that Centos uses the Anaconda installer, which seems to be designed to deter people from installing the operating system. In particular partitioning is a nightmare (I find it works best by setting up your partitions before running the installer).
I would recommend Centos to people who are learning Linux system administration and/or who are simply looking for a distro that's stable and doesn't need to be reinstalled any time soon.