5-mans are still my favorite part of the game. Guild runs, PuG-runs, something in between...doesn't matter. And I've had a fabulous time in Northrend 5-mans so far. Yes, Herald Volazj is pretty much the clear winner of the early 5-man bosses (gotta love that Insanity debuff), but Azjol Nerub's been very popular, and the questline leading to the cutscene at the end of Drak'tharon Keep is getting a lot of good press. Not enough people are in the late '70's or at 80 to have had a good crack at Halls of Stone, Halls of Lightning, Utgarde Pinnacle, or Culling of Stratholme, so I'm not sure how those are going to go over, but I think players in general have really enjoyed the new dungeons.
That there's markedly less emphasis on soul-crushing trash (I'm looking at you, Shattered Halls) and more emphasis on cool boss mechanics and gorgeous scenery is also pretty awesome. And then there's that giant drop in Azjol Nerub taking you past several levels of the ancient city that never fails to kill someone. I shouldn't find it funny, but I do, even when it's me.
How far along are you on the new Northrend 5-mans? Have you picked a favorite yet? And how many people have you seen die on the Azjol Nerub drop?