There's over 150 enemies and many friendly npcs the bosses are pretty diffacult but rewarding nearly every boss has it's own unique trait for example during the first boss not only do you gain no soul well attacking him(due to his armor) unless to knock him down(translation he only gives soul during his stagger) and during the fight rocks are falling down onto the stadium
After a certain point you get the "hunters jornal" which records the enemies you've killed and after beating them so many times you get
The "hunter entry" which is typically something written in by the hunter
Ex "a filthy creature that is happy to chew on any old thing it finds discarded on the cavern floor. When it notices a threat it will annoyingly shriek. So kill it swiftly" -the hunter on vengfly king one of the first bosses