I've been looking at the latest release of RedHat Enterprise 7 and its 'clone' CentOS 7 recently.
Sum it up in a single word? DAFUQ? (is that technically one word?).
If you currently run EL6, for $diety's sake, stay on it. There are so many problems at the moment that you are much better to stay well clear until the dust settles.
List of current issues:
- rsyslog - no longer works. Everything is now in a 'journal'
- logwatch - no longer works. Does not support journal logs
- gnome3 - If you use a desktop, you're pretty much forced to use Gnome 3
- systemd - requires all kinds of hacks and workarounds to get anything more than basic functionality
- systemd - Service files missing from a lot of tasks (eg: BZ 1060347)
- up to 50% speed reduction in virtual machines - BZ1104748
- No thunderbird packages available as yet.
- No Xen Dom0 support in EL7 - despite the upstream kernel version supporting it
- Wholesale shipping of packages out to EPEL to avoid support requirements
This is just scratching the surface at the moment... There are many more gotchas just waiting to bite.