The new user experience includes a new BlinkFeed, and the photo gallery application has been updated as well. HTC added a do-not-disturb mode, simplified the lock screen widget set-up and is said to have improved low-light camera performance.
We are not sure how long it will take AT&T and T-Mobile to warm up the servers and deliver the goods. Once we learn the update is being pushed out, we will let you know. Updates are usually pushed out in phases in different markets.
All we have to do now is wait.
UPDATE: Well that did not take long. A tipster in New York just sent us screen shots of the update to Android 4.4.2 on his HTC One with T-Mobile. The file is a little over 560MB, so it is a good idea you have a solid network connection available prior to download.
sources: HTC (Twitter) via Droid Life