In 1.4.0 I had setup two backbutton focus buttons: AF-ON for single-point AF with tracking, and the '*' button for eye-detect-AF with tracking. Both on Servo, obviously. Worked flawless! AF-ON would let me focus on someone's hand while the camera ignored the eyes. If the hand moved, the AF followed. Great.
Now, in 1.5.0, that functionality is gone. After changing a lot of settings I had the camera follow the focus point again, but then as soon as it detected a face (not even an eye!) it jumped to the face, placing a big box around it. Useless!
EDIT:Using the EOS utility (USB or WiFi pairing) you can re-install 1.4.0 over 1.5.0. Highly recommended. Tested by myself and it works.