12.0.0B1 and client bugs:

BootPlayer during JOINGAME leaves blank entries in the server's online user list
XXX New interface doesn't have enough space for map editor
Alt-clicking doesn't work with Box on
XXX GetMapSetting should be a FUNCTION, not a SUB in mbsc.inc
Separate bookmarks for each tileset
The server-side script editor doesn't have the new features
OOO Scripts with many loops sometimes stop mid-script
You can get 0 of an item through scripts and modifying character data, but you can't drop it
Right-clicking in the map editor makes objects on the ground that can't normally be seen show up

Requested features:

Interface font color
Find feature, bolded script names, and/or alphabetical ordering in scripting events list
Servers on different ports
Minimaps
Raised limit on Objects and Monsters
Raised limit on stats
A separate map editor with easy-to-use interface - possibly one that can edit multiple maps at once with a grid showing map edges
MissPlayer and MissMonster subroutines