I have been one of those who have resisted the new itunes 11 since release. However, I recently changed my Mountain Lion installer from the original 10.8 to 10.8.3 that Apple provides - and during a recent system reinstall, wound up with itunes 11 by default. Instead of reverting to the previous version like I did after the original 11 release, I've been trying to live with 11...
However, I cannot get 11 to display my iOS devices - iphone 5, latest iPad. I have all the current updates on the iOS devices, iTunes, and OS. I've tried rebotting the devices, the computer, reinstalling iTunes. I've tried every USB port and cable - no success.
The devices show up in everything else - iPhoto, Image capture, etc - just not in iTunes.
You may have the "Devices" list hidden. Have you hovered with the mouse to the right of the caption "Devices" in the sidebar, until you see the hidden text button "Sow" or "Hide"? Press "Show" - does that reveal your devices?