First things first: this is not an EFI BIOS (although, technically, EFI is more of a replacement for the BIOS than a specific kind of BIOS). Gigabyte's 6-series motherboards still use an old-school Award BIOS. However, they incorporate an EFI bootloader to enable support for hard drives larger than 2.2TB. You'll need a Gigabyte software utility to use the full capacity of those drives on older operating systems, but the app isn't required for Windows 7 x64, which is the OS we expect most folks to be running with 6-series motherboards.
Native support for 3TB hard drives is one of EFI's most important features, and this bootloader approach appears to deliver the goods without replacing the entire BIOS. Credit Gigabyte for coming up with a novel solution. However, the bootloader doesn't address the larger problem of Gigabyte's current BIOS interface being clunky and downright slow to load some screens.
Then there's the matter of the BIOS's fan speed controls, which are quite a bit more limited than what you get from Asus and MSI.