Monte Cook said that the power progression in AU is more linear than in D&D, with more powerful characters at low levels, and less powerful at high levels.
Which may be the case.
However, AU characters gets 2 feats at first level, rather than 1 (plus human or class bonus feats), so removing this additional feat to have them in-line with D&D-classed characters remove the greater power in low levels, and leave them with the lesser power in high levels.
That said, and for comparison's sake, here's the unfettered:
Good BAB, good Ref, bad Fort and Will. 4 skill points, with a wide range of roguish skills, and d8 HD.
Bonus combat feats at levels 2, 6, 10, 14, 18 and 20.
Sneak attack +1d6 every four level (4, 8, 12, 16, 20).
Parry: the capacity to add their Int bonus to AC against a single opponent in a round, with the added restriction that this bonus can't exceed half the unfettered level (minimum 1, however, otherwise it would make no sense being a 1st-level ability ever). It works only on melee attacks from one opponent the unfettered can see.
(Personally, I like the house-rule that base it on Cha bonus instead -- all about feinting the opponent.)
At level 7, the unfettered may parry ranged attacks. As he can only parry against one opponent in a round, he can't use parry against a ranged attacker and a melee attacker at the same time.
At level 9, evasion.
At level 13, he can parry spells. One spell per round, can't use the other parries in the same round, opponent must be visible, the spell's casting must be visible (so can't parry a spell without verbal or somatic components), the spell must targets him specifically (no area spell); and he must have a magic weapon to parry spells. Parrying magic works differently from parrying attacks, he makes an attack roll opposed to the spellcaster's caster level + ability modifier check; and if successful, he merely gains a +4 competence bonus on his saving throw.
The unfettered don't get Weapon Specialization.
It don't see this class as being madly overpowered. Less feats than a fighter, less hit points, less AC overall, in exchange for a bonus to AC against one opponent (handy for a duelist, but still not necessarily bigger than the bonus of an armor with magic enhancement), sneak attack, the capacity to save better against one spell from time to time.