Few days back Microsoft said, “To ensure the best experience for our customers during the holiday season, we have taken steps to remove the update for Surface Pro 2 that was previously published through Windows Update on December 10,” and even confirmed that they are working to release an alternative update package after the holidays. It seems, Microsoft has changed their minds and decided to deliver the fix earlier than expected.
Here is the info from the Support forums,
We are working through the holidays to deliver a fix for the small number of customers that have experience decreased battery life and booting/sleeping problems as a result of the December update. We took the update down to prevent additional customers from ending up in this state. All hardware failures, none of which are known to be caused by the December update, are being handled promptly through our warranty exchange policy.
The UEFI firmware that we released in the December update prevents some devices from entering sleep mode (and other low power states) properly during periods of inactivity. In order to release an updated version of the UEFI firmware we need to test the new version with the other drivers in the set to make sure we are not releasing yet another unknown state to customer machines. We certainly feel your pain and assure you that we are doing everything possible to make this right, as quickly as we can.