what shall I tell you about Dawn of the ages to convince you to give it a try at least?
I won't talk much about the common stuff like different classes (professions) and specializations (careers), different clans, different religions, different races (reincarnation into an elevated race also possible), the option to choose between joining PK (with pk-range) and not joining and all the other details most muds have. Had to mention it though ;o)
Instead you should give it a try because of its uniqueness. Large parts of the world are handmage just for dawn and are under permanent construction. A lot of work is put into the atmosphere. There are also a lot of quests. You could have to search for an item, execute an assassination or browse through the large cities' libraries to find some lost knowledge. Just a few examples of course. Your reward might differ between "just" increasing your knowledge, gaining Questpoints, which can be spent for really nice items, an item of usually high value, a potion with that nasty spellup you always have been looking for...
There is so much more to tell, I'm afraid I can't put it all into this small message. It's up to you to try. Have a look at the homepage http://dawn.netcologne.de as well. You will find almost everything explained you need to know and once entering the world of Ayreon questions sent over the newbie-channel will be answered very kind.
Come and play :o)