By the time of the invasion of Japan, Qubilai's Yuan armies had changed considerably from the steppe horsemen of his grandfather's day. Even during the Mongol civil war, infantry were a large proportion of his armies.
The current unit mix is very diverse and the Mongol player has quite a few varied options, which all goes to improve the gameplay. Battles have been very intense and tactical, Japanese units have also changed and there are new maps with more on the way.