My experiences with Ubuntu 12.04 LTS and UEFI
Installing Ubuntu 12.04.2 via UEFI: First didn't work on USB disk, had to mount via ISO.
It still wouldn't setup correctly. This took about two hours because my USB disks were only USB 1.0.
Installing Ubuntu 12.04.1 via UEFI: worked straight away (maybe a USB disk error? but the USB disk is brand new).
However I couldn't at all get the machine to boot straight into Ubuntu after install. The machine would get stuck on "Windows Boot Manager: The boot selection failed because a required device is inaccessible". Of course it was inaccessible - I reformatted the disk to install Linux. Pressing F10 to manually select ubuntu as the boot disk would work fine, but I had no way to set this UEFI boot disk as default.
I did almost everything I could think of: update the Grub entries (but the problem occurs before Grub is even loaded), removed the boot entries using efibootmgr, made sure that the boot order was correct in efibootmgr, even manually removing files from /mnt/boot/efi/EFI/Microsoft (which just broke it further). It seemed like there was a boot entry that couldn't be removed or reset by the BIOS (reset to defaults did nothing), and asserted that a Windows would always exist.
Boot-repair was often recommended, but this requires a GUI (i.e. X11) to run.
Another option was to fix it using a Windows repair disk, but then you'd have to reinstall Grub afterwards anyway - didn't seem like a reliable option.
Finally I got some sense and disabled UEFI boot completely, and had to reinstall 12.04.1.
Installing Ubuntu 12.04.1 without UEFI: Straight away things were better: a graphical boot menu for install, rather than a text menu.
The rest of the install was identical. Now my machine boots perfectly into Ubuntu every time. It also means that my UEFI install is completely broken and I can never use UEFI for anything except Windows.
Lesson: Don't use UEFI unless you are absolutely certain you are only ever going to use Windows on your machine. If you want to use Linux with UEFI, you HAVE to (somehow) remove the Windows UEFI boot manager before uninstalling Windows.