EviliroN: I've also been playing it with the last patch Micropose put out (although I wouldn't mind trying out this 1.4 patch).
I'm not really sure what your beef is when it comes to wizard customization. There are always going to be stronger options to take in similar circumstances. That doesn't mean having those other options is bad, or necessarily mean bad game design. I would rather have too many options, including ones I would never personally choose, because they are weaker or don't cater to my playstyle.
I will give you the fact that the AI is bad at using spells, although that is a pretty common issue in any game of this type. Spell balance is also pretty weak in some areas (crack's call was the worst) There are also a lot of unique spells, several types (global enchantments, unit enchantments, summons, tactical only spells)
Game mechanics wise I would say the following are strong:
Magic system (nodes, mana/magic producing buildings, faction bonuses, magic power allocation into mana, research and skill)
Factions/Races (Lots of different units types, faction attributes that affected several areas of gameplay: city growth, magic production, unrest levels, unit abilities like flight, water walking, buildings that were available)
Unit/Hero Abilities (Level Scaling abilities like Might, Agility, Constitution, Blademaster, life stealing, first-strike, healer, magic immunity, pathfinding etc, illusion, wind walking, poison, firebreathing, thrown weapons, luck to name a chunk. Also, a large part of the heroes have randomly occurring attributes meaning they have much different power potentials each game)
Randomized Map (I believe MOM was the first game to have fully randomized maps. There are always very different configurations, although sometimes that didn't work out so great. This also includes the randomized lair, etc encounters.)
City/Resource System (Decent variety in building types and resource types. Neutral cities provide a good level of early game challenge, although sometimes there weren't very many and lacked in race variety.)
This is not exhaustive, but I'm running out of steam at the moment.
As for strategy, you can prioritize spell research/mana/skill with your magic powerbase and spell research choices, races give you several play options (burn Klackons with fire!), wizard customization, randomization of spells available, prioritizing building order, city founding based on surveyor, securing access points between the different planes and choke points, securing cities with specific races.
Also not exhaustive, but I think demonstrates some significant strategy options.