I'm one of those people who have a hard time putting books down when they've caught me -- and Armageddon is even worse. I haven't found any other mud with the deep immersion in the character, even down to the think command and the having to submit a background, with such careful and meticulous documentation of the world so you know what's going on before you get there, and with a world so intricately and beautifully created, down to messages about the sunrise in Allanak's main bazaar, or the torches flickering on Caravan Way at night.
It's not the easiest mud in the world by a long shot -- but well worth the time spent making a few characters and getting the hang of it...unless you actually wanted some free time.
The staff stays behind the scenes, but they seem to be continually adding and improving to their creation. Just recently they added tattoo code -- your character can go get a tattoo from an NPC merchant and when someone looks at the character, they can see the tattoo's short desc, or can look at that specific body part and see the whole description. Plus if you're wearing equipment over the location, the tattoo won't show up. Not a huge thing, not another race or skill or whatever, but incredibly atmospheric.
To new players, I'd strongly suggest looking at the website, particularly the introductory section, which will considerably shorten the learning curve.