The team over at Bioware Austin is delaying the release of the new Game Update 5.2 by at least a week due to some quality issues:
We want to ensure our updates release at the highest quality possible and Game Update 5.2: The War for Iokath is no different. At this point in time, we are not satisfied with the quality of the Iokath update. For that reason, we are delaying the release of 5.2 by one week, to release on April 18th. This allows the team more time to make improvements to address some of the issues still pending. We did not make this decision lightly as we are very eager for all of you to get your hands on the new storyline, reunite with old Companions, or try your hand at taking down the God of Rage himself.
As soon as we know timing for the next maintenance I will post that information. Thank you all for your patience and understanding. We do apologize for any inconvenience this has caused. We will post the patch notes either today or first thing tomorrow so that you know what is planned for 5.2!