At first promised to come at launch with RoR, the instances were delayed and split up into 2 releases. The first of these releases will be reviewed here, the 2nd is still on its way.
All 3 instances are 3-man, levels 20-85. There's a startup quest in Bree, but it isn't required to run the instances.
This instance has you retrieve a stolen eagle egg from the frost giants up in the Misty Mountains. It's basically a winding path up the mountain side. Along the way, you'll be harassed by the giant who throws boulders at you.
The first boss isn't really anything special. He summons adds and you have to avoid the giants' boulders.
The second (and last) boss is somewhat different in that the egg gets its own health bar. You have to defeat the giant while keeping the adds he summons off the egg.
Seat of the Great Goblin
The goblins are bolder than ever before. This might be caused by a new Great Goblin. Head into the tunnels under the Misty Mountains to dispatch him before things get ugly. If you've been to goblin-town in the Misty Mountains, this place looks familiar. Be prepared for large groups of low-morale mobs.
The first boss is basic tank-'n-spank, while at certain morale thresholds, he becomes unattackable and does a ground-slam. Occasionally, rubble will fall down.
Second boss is somewhat spoilerish in its tactics. I'll only say that the fight isn't over as fast as you'd think.