Anyone happen to know of any must have mods or unofficial patches for the game?

Not must have, but some prefere to use them.

Begin with these:
http://www.heroesofmightandmagic.com/heroes5/mods_and_fixes.shtml

Fonts pack:
http://www.maps4heroes.com/heroes5/mini_patch_eng.php

The skill wheel:
http://www.gog.com/forum/heroes_of_might_and_magic_series/heroes_v_skill_wheel

Graphics Overhaul mod:
http://heroescommunity.com/viewthread.php3?TID=37356&pagenumber=1

And many combat field mods. They change the combat grid and panels. And add a wait button. Without it, you have to press 'w'. There are too many to pick one.

Well, I'm an idiot.

I don't know why I never even thought to check the HC forum.
Thanks for the recommendations, that graphical overhaul mod and the font mod look pretty amazing.

My definite recommendation is the AI patch currently developed by a dedicated fan and soon to be released...

http://forum.eternal-essence.com/

The available pre-version already improves the AI significantly, but the full package might be a kind of revolution according to the developer.