Since 3.3 dropped the dungeon finder has been talked about.

Endlessly.

Instead of talking about it in technical details I wanted to talk about my experiences with the various groups when using it.

Type 1: Run of the Mill.
The vast majority of these groups are groups that are pretty typical make up of toons in their traditional roles without huge variations.  These are usually successful and I generally get a good tanking experience out of them.

Type 2: Huh.  That works, I guess.
These are the groups that have a couple of odd toon roles in them, Pally healers, DPS warriors, shadow priests…  These work out OK as long as the player knows their limitations and abilities.  I generally have decent tanking experiences with them, though the heals can be iffy when I get hit with Spike Damage, which Death Knights are really susceptible to.  Frequent problems are newbie melee DPS who don’t fight from behind the mob and cause frequent spikes in damage, which is bad for my survivability.

Type 3: The Bwah?
I have had only a very few of these.  The most memorable was the random Gundarak which is one of my least favorite instances, for various reasons.  My group was this: My charming DK self as tank, on DPS were Warrior, Warrior, Warrior, and Pally healer.  The problem, The warriors weren’t running omen and not watching their threat and the pally was Retribution specced. This.. did not work.  The pally couldn’t actually heal anyone.  Not due to incompetence, but because something was preventing him from actually casting the spell on the target.  It became rapidly apparent we were going nowhere rapidly.

The overall experience has been positive, but the few bad ones stick in my mind more than the majority of the best ones.  I am however, learning a number of the fights and should be able to stay ahead of the curve in the heroic fights. The emblems are a nice boost to acquiring gear, though I need to work out a bit more gear for Heroics before feeling somewhat confident in the overall gear.