The new Dungeons player limit might be considered by some players as a nerf. However, dungeons will be more challenging than the usual zerg fest of 10-15 players.
Blizzard: "They say that there is strength in numbers, but does a victory won by force alone truly taste as sweet as an enemy conquered by the courage of a few brave souls? The high-end dungeons of World of Warcraft have received significant updates to their loot, making the items that can be found there much more desirable than before. To present adventurers with a challenge worth the epic rewards, the maximum number of players for each dungeon has been decreased to five for Blackrock Depths, Stratholme and Scholomance, and ten for Blackrock Spire. Brave the darkness, and claim what is rightfully yours!"