Each tree has about 10-12 skills each, divided into 6 "tiers", of 1-3 skills each.
This Although this skill tree system was the official skill system for quite a while on Diablo III, Blizzard is, of course, subject planning to further change as the development process grinds onskill system removing the tree-type architecture and possibly moving into a purely skill-based system.
The overhaul did also see the removal of many relatively redundant skills, primarily removing [[passive skill]]s.