The ROG BIOS has an absolute bucket load of options when it comes to getting down and dirty with the board. Of course, it also uses the popular UEFI interface that we're seeing not only on all ASUS boards these days, but most other boards as well.
Looking at the BIOS, you've got the ability to do an easy overclock via CPU Level Up which will push your 2600k to 4.2GHz or 4.6GHz, otherwise you've got the option to really mess around manually with everything to try and achieve the strongest overclock possible.
As you move throughout the BIOS there's nothing too out of the ordinary that really stands out apart from the massive list of changes you can make. EZ Mode is still present, but when going into the BIOS the Maximus IV Extreme does default to the Advanced Mode.
The Maximus IV Extreme BIOS can be quite daunting to some people, but you've got options to overclock other ways if you're not confortable editing the BIOS.