Just like anything, there is good and bad.
Unfortunately for me, my experience with Oracle education has been predominately bad and former manager experienced the same where he was able to retake a course almost a year later since the original was unrealistic for real world scenarios.
With Oracle education, the most simplistic setup is used, e.g. no ASM, no Grid Infrastructure as it may add a little more complexity to set up?
A little advice, try to find out who will be the instructor before registering for the course. Call and ask.
Next, there is a large and great Oracle community where you may learn more about technology and new features.
Here are 2 features I came to know from twitter feed and blogs which were never covered in the 12c Data Guard Administration.
ROLLING FORWARD A PHYSICAL STANDBY USING RECOVER FROM SERVICE COMMAND IN 12C (Doc ID 1987763.1) (Courtesy Nassyam Basha)
RMAN ACTIVE DUPLICATE USING BACKUPSET IN 12C(NEW FEATURE) (Doc ID 1987193.1) (Courtesy of Deiby Gomez)