Blizzard Customer Support has also confirmed that the issues are being investigated:
We're looking into the #WoW server stability, folks! Our technicians are on the case! Updates to follow.- BlizzardCS (@BlizzardCS) December 19, 2013
The responses to the tweet imply that the lag is the most problematic part of these technical hitches, with players reporting very high MS on their connections. However, not everyone is affected, as my latency is only 70 MS, which while higher than usual is far from problematic. Blizzard's tech team are working hard to rectify these issues.