I like realms of despair a lot. I've played several muds, and of all of them I have found the Realms of Despair to be the most enjoyable. New areas and classes come in frequently, and the immortals frequently hold quests with special unique prizes. There are a lot of dedicated immortals and players who come out every month with the 'cry of despair', which is an online newspaper. When the immortals play sadistic games and brutalize the players, it reminds me of my home in 1941 Germany. Oh, how I long for those halcyon days. Furthermore, the player base of 500 online at the same time is very much like a gulag back in the vaterland.
Role playing is encouraged, and there are special race-talk channels which facilitate wars between the races. The pkill is really fun, sometimes, except I noticed that the deadlies are often a lot crueler than the other people.
Realms of Despair is highly addictive, and I recommend it without hesitation.