The folks over at GuildOx, a guild progress and achievement ranking site, were kind enough to email us some interesting new statistics about Ulduar's achievements. As it stands a large portion of the raids are, of course, not getting encounter specific achievements the first time they go into the zone. However there are some that are getting them nonetheless.
People may wonder if guilds are getting the achievements this quickly because Ulduar is too easy. My opinion on the matter is that Ulduar itself sans hard modes won't be abnormally challenging, however when you put in the hard modes and various twists to the encounter in order to earn the achievements, Ulduar is going to become quite challenging.
The achievements that have made the list so far, like A Quick Shave where you have to kill Razorscale with her only flying into the air once, just requires a lot of DPS. That's not too hard for most geared out groups to muster.
Take a look after the break for GuildOx's list of the top five Ulduar 10 and 25 man achievements, and head over there to take a look at things overall.