Enchantment spells affect the minds of others, influencing or controlling their behavior. All enchantments are mind-affecting spells. Two types of enchantment spells grant spellcasters influence over a subject creature.
For a list of all spells which are of the school of Enchantment, see: Category:Enchantment spells.
It is hard pressing on a good wizard to give up Enchantment since most of the spells effects make otherwise difficult battles much easier. Holding or making a target go to sleep allows allies to easily strike down otherwise tough creatures.
Since a great amount of enemies in D&D are fighter-based for saves, meaning low will saves, Enchantment proves very effective at overcoming the problematic monsters in this regard.
Defensively, there are nearly no spells - only Heroism provides any decent benefit. The main reason to choose Enchantment is to gain the benefit of all the Charm, Dominate and Paralysis spells, which are all heavily based on save-or-die-by-allies - ie; making them very easy targets for your allies.
The spells are less useful for casters with lower ability scores or who cannot afford spells which are rendered immune against certain monsters - Sorcerers with many Enchantment spells would be rather useless against the undead, or any constructs, while a Wizard or other caster can easily prepare different spells for those situations. Taking spell focus in this school, if heavily used, is highly recommended.
The changes from 3.5E are probably least with Evocation and Enchantment. Enchantment spells do not allow you to command creatures you dominate or charm, but do become your allies and attack your enemies. Most of the Enchantment spells remain intact.