Bad
Mint
Unique building for the Malinese; Replaces Forge
+1
+25%
+10%
Can turn 1 citizen into Engineer
+1 from Gems, Gold, Silver
If you ran 100% wealth for a few turns to save money and maximize the use of the Mint, you´d still be receiving way less bonus then you would on research with only a library in cities, which gives +25% . Saving money on 100% wealth to maximize bonuses if anytime is effective with markets, grocers and banks build. Those together though give a bonus of +100% - so the 10% of the Mint doesn´t play any role either.
A forge is a forge even if you call it a Mint and give it some kind of weird castle thing as a picture. Or what´s going on in that art :P ?
Good
Ger
Unique building for Mongolia; Replaces Stable
+4 XP for new Mounted Units
In earlier eras - whenever you´d have build stables anyway, you´ll be happy about the 2 additional experience points bringing you one fight closer to the next promotion level - which can potentially make the difference during an attack with Kehiks, the Mongolian horse archer or with Elephants.
It gets really interesting when you start combining the Ger with Vassalage and/or Theocracy and/or the Charismatic trait. Either two of those combined with barracks and the Ger result in tripple promoted mounted units. That can be Horse Archers or Elephants (Medieval), Knights (Renaissance) or Cavalry (Industrial). A charismatic Mongolian can build tripple promoted cavalry without having to leave Bureaucracy for Vassalage.
For Good UB - Bad UB part #1 click here
For Good UB - Bad UB part #2 click here