The following is a list of changes made specifically to class progression or unique class abilities.
Arcane Archer
Arrow of Death: The DC has been changed to 20 + 1 Per Arcane Archer level.
Assassin
Hide In Plain Sight: Now received at level 8. Improved Sneak Attack: works for Assassin without Rogue/BG sneak.
Barbarian
Barbarian Rages: The stat bonuses of their rages are removed and replaced with equivalent ab/saves/hp/discipline. (Standard = +2, Greater = +3, Mighty = +4) Their speed bonus now stacks with haste, so a barbarian is faster then everyone else besides monks.
Bard
Bard Song and Curse Song create an area of effect. You are unaffected by them if you are silenced or deaf unless you are the caster. See the table for the detailed information of the effects on the forums (http://dev.sinfar.net/p_bardsong.php). Lasting inspiration doubles the duration taking into effect the bonus from lingering song. (so 30 rounds total)
Cleric
Animal Domain: Adds +1 to Strength, Constitution, Dexterity, AC and AB with each 6 caster levels, up to a maximum of +6 to the affected summons: Summon Creature I, II, III, IV, V, VI, VII, VIII and IX.
Dwarven Defender
Defensive Stance uses are unlimited and the bonuses have been changed: http://nwn.sinfar.net/p_defensivestance.php
Monk
Their speed has been lowered from 10% to 3% per 3 monk levels.
Pale Master
They lose 1 AC at first level and 1 every 4 levels after that. Epic Pale Master get 1 real caster level (not only extra spells) every odd levels (11, 13, 15, …).
Red Dragon Disciple
At level 10, they get +2 Strength (instead of +4) and no AC bonus (instead of +1AC).
Shadow Dancer
Hide in Plain Sight: works on anyone who is 5 feet away from the player. Shadow Evade: always has reduction power of +6, the concealment continues to increase at epic level by 1 per epic shadow dancer level, the AC bonus increases by 1 every 10 levels after level 10.