Slorkuz (WoW-Europe) announced upcoming hotfixes to solve certain bugs in patch 2.4 that may cause items to work improperly.
Power Word: Shield sound was a bug, slated for fix in an upcoming patch.
As far as I’m told, no sounds were intentionally changed from 2.3.3 to 2.4.0.
Wow Europe Game Time Credit
On April 8th a technical issue caused 6 hours of downtime for the realms of the Crueldad, Hinterhalt, Némésis and Nightfall Battlegroups.
As a result we will credit all players with an active character on the affected realms with 1 day of game time credit. This will be credited to the eligible accounts in the next few weeks. Please accept our apologies for the inconvenience this has caused. (Source)