This product provides a very generic overview of the different types of mounted combatant known in the real world, with an eye to informing choices for those who'd like to play a mounted specialist.
The concept of having different kinds of mounted fighter is sound, but the descriptions given are not really specific enough to give you much of an insight as to what makes each one distinctive, although there are some useful hints about which feats or skills would be useful, and which races or core classes are most suited to each role.
Illustrations are nice, layout is a little strange - double spaced and looks as if the intent was to pad out the work to increase page count. The language is a little unusual too, perhaps an editorial eye might have helped.
If you want to play a mounted combatant, this might be worth a glance as you formulate your concept.