Over the past few days, I've killed the first 2 spider bosses in Naxx (10), Sartharion (10) and Archavon (heroic 25), the former two with my guild and the latter with less than 25 in the raid.
Considering I'm still half geared with level 70 items, I can see how Ensidia, the new combined SK/Nihilum guild, was able to clear the WotLK raiding content so quickly.
I realize that Blizzard wanted more content for the casuals and I think it's a great idea in general, but that "epic" feeling of facing a difficult encounter (Kael and Vashj, Naxx at 60) hasn't hit me yet.... mainly because the strategy employed for almost all dungeons (normal, heroic or raid) has been to just tank everything and AoE it down.
One could argue that Achievements are where the real fun is, but to me they're only something to brag about because they're not really part of the original encounter.
Luckily, I'm still only in Sholazar Basin with my questing, and the thrills are coming thick and fast from the lore direction. Here's hoping that by the time I clear the quest log, the wow factor will be back in raiding - I'd be disappointed if soloing BC heroics or Onyxia ended up being more exciting for me than downing the newest raid boss.