Spoiler alert: this video shows a successful kill of Kael'thas, the final boss of the new 5-man Magister's Terrace in patch 2.4.
It looks like quite a fun fight, although that Gravity Lapse thing will probably annoy the hell out of me. But hey, he drops an epic and a rare, even on normal mode! That's worth something. Check out Blizzplanet for a text description of the fight and strategy. And finally, below are clips of the rest of the fights in the dungeon. Overall it looks like a cool place.