This might be something more for the Exadata forum, but, hey, I'd thought I'd ask here anyway...
From what I've been told (for about 18 months) by various Oracle people, 12c OEM (do we call it 'Cloud Control' or 'OEM'?) is meant to play a lot nicer with Exadata than the 11g OEM does.
'Fantabulous!', I say, because working with Exadata on 11g OEM is quite frustrating (especially with the storage cells and the ASM stuff).
Anyone had any experience with this? Is it really worth upgrading ESPECIALLY if you have an Exadata machine? The reason I'm asking is that we're looking to possibly building a 12c OEM to handle our Exadata and 11gR2 systems and then keeping our 11g version for the 9i and 10g systems that we have (I know, I know, believe me, I know...).
I'm considering suggesting it as part of an Exadata upgrade project rather than having it as its own standalone project.
I've found OEM 12c to be a huge step up from 11g for Exadata management, particularly in terms of initial setup. If you've gone through the process in 11g, you'll know there are many plug-ins to deploy for full monitoring: InfiniBand switch, Cisco management switch, KVM switch, ILOM, PDU, etc. I've also found agent high-availability in 11g to be quite complex to configure.
12c on the other hand has the concept of an entire Exadata system, and can manage all the Exadata components centrally.
Also, in 12c we've started to see the capability to actually make configuration changes to storage servers rather than resorting to CellCLI; IORM for example now has a slick new interface for creating and managing resource plans.
I'd suggest prioritizing a 12c OEM upgrade to happen before your Exadata upgrade, so you can avoid the pain of an interim 11g OEM configuration, and having to change it soon after.