Based on personal experience on another mud (grain of salt):

(- Could brief be made more selective? Idc if it takes 59
levels to learn 'brief look,' 'brief exits' should be there
from lvl 1 imo.)

- Consider endorsing the prepackaged mudlet client as a
recomended client. The idea of having to choose/configure the
client that connects you to a game is completely alien to
modern audience and for good reason.

- Consider player-client-visible RoomID (where reasonable,
ofc) or other Mud-side changes to facilitate infallable pre
configured auto mapping. (perhaps there are some in game
quests or character progression milestones that you could tie
the unlocking of this feature to?)

Amazing though your diku wizardry is proving to be, UX is a
single point of failure for player retention in my experience.

Maps here do not compete with even other muds to be perfectly
honest. 

Why don't I have a visual representation of which immediate
exits my character sees??

If I seem critical it is only in my search for maximal
retention/effort_unit. Really all I have to say is: CLIENT BIG
IMPORTANT.

PS. Mudlet client's 'GUIHELP 11' does not link to the correct
pile of strings.