There is a .pdf document that lists all the changes in the update. Here is the Foreword:
The changes in this version were primarily motivated to 1) balance
races, units, heroes, and magic realms; 2) edit out or around the
various bugs in the game, including many spells; and 3) fix a wide
number of text mistakes and ambiguities.
The end result is that there should be a reason to make every kind
of unit, at least in some game circumstances, making combined
arms a little more common than in the basic game. In so doing, the
AI “should” be a little better, as their inefficient choices are better
rewarded.
All thanks to Aureus
December 19, 2008
Some interesting stuff, I still have my 3.5" disks for the game so may just load it up. 
The website dedicated to MoM also has a number of other interesting downloads. Check it out.
