MoM was fun because of the number of choices you could go thro in the metagame.
Units, heroes or fantastic creatures?
Death or life, nature, chaos or sorcery?
Mana, research or ability?
Mastering a single spell school or being well in a few?
Which of the 12 distinct races?
Which of the ~300 spells (across all the schools) should I cast? They are all good, after all.
City building- you got all the options right at the start. Should I rush the race's super unit, build the city, or city spam?
Should I build a few good units to protect my city, or I can manage with the pikemens to reduce unrest?
Each one of these question is inherently different than, say, civ games. In civ games, the only questions left is the city building, and slightly the unit decision.
The biggest problem with the game was bugs and AI, but the 1.4 insecticide mod did a nice job- the game on the hardest setting is indeed not an easy one, now.
For these that say that It's impossible to lose is MoM, I just lost a game a week ago. Everything was going well, I thought I was winning and then BAM! Timestop. He starts casting Spell of Mastery. I lose.
I got Checkmated by a computer with crappy AI. How many times do you see that happening, huh?