[+] Good Models and Icons - the models you used are just perfect! good work
[+] Custom Spells - you used a good variety of custom spells, that is a good work too
[+-] Weird buildings: the models you used for the scourge building are't so good, try to find something diferent or just use the commom undead models
[+-] Workers attacking: - you used a zombie model to replace ghouls, but that kind of model don't fits as a offencive unit, try to make them do not attack enemies cities or creeps, or just use normal ghouls
[-] Tooltips "missing": - all of the custom units, buildings and spells tooltips are just nothing: points, comas, bars etc. But they say nothing
[+-] Idea isn't very original: