On Samsung S5 AFTER installing KitKat last week, the mm-qcamera deamon usage has drain down full battery in 7hours (before update 12+ hours uptime was the average. Hopefully an urgent fix is coming. So far the key argument for me for Android was the lack or quick fix of bugs...
There is a bug report that has been filed to AOSP about this with a FutureRelease status (a bug fix will be coming soon). Read it here.
It seems that a reboot provides a temporary fix for the problem. A factory reset fixed the issue permanently for most users.