A small but increasing number of users are reporting extremely poor battery life issues after getting the OTA Android 4.4 KitKat update for the HTC One. The problem doesn't seem to be targeting any specific carrier either, as users who have reported this range from Sprint to T-Mobile and others.
There is a thread on the subject over at our sister-site @ HTCOneForum.com. Here's the link: Battery Drains Fast After Android 4.4 Kitkat Update - Page 2
Perhaps we might be able to narrow down the issue with the greater resources found here on DroidForums, so we wanted to share it over here as well. We have not found any official word from HTC on the subject just yet, but will keep you posted. Sound off in this thread if you have experienced this problem, and might know more about it or a solution.