My 2 cents:
1) The requirements for natural finesse are shaky.
For Fighters:
A) A fighter with a 13 or, especially, more Str is better off just using Weapon Finesse, since Str damage with 1 weapon is better than Dex bonus with many. Most fighters end up with Weapon Specialization and Weapon Focus anyway, so they are going to end up concentrating on one weapon and the rest are going to fall by the wayside.
B) Depending on how stats are decided (point buy, 4d6) most fighters can ill afford a 13+ Wis. They are, of course, better off with Con and Dex bonus. Even a high Int is usually more valuable, adding needed skill points, required for Expertise and, more importantly, adding AC to the Duelist, a class tailor made for the finesse warrior.
For Rogues and Monks:
A) The feat seems tailored towards the Rogue (traditionally high Dex and who have many important skills linked to Wisdom) and, especially, the Monk (high Dexterity and Wisdom essential). But, Str is usually a low priority for Rogues, especially when it will be of literally no use with this feat. Monks with unarmed attacks will also see diminished returns with the feat (though they are better off than the Rogue) as unarmed blows, their most common attacks, will only have a damage bonus with a 14+ Str.
B) Monks don't have off-hands with their unarmed attacks, and only rarely with their special monk weapon attacks, so the 1/4 Str to off hand attacks won't mean much. Not a big concern, but the feat description does seem pointed towards them, so....
C) Most importantly, neither Monks or Rogues have proficiency in all simple and martial weapons.
2) Tumbling Pass.
Too much in my opinion. Yes, the requirements are high, but nothing that an average monk or, especially, rogue won't have at 12th level. Here's the real problem I see:
A) Typical 12th level adventuring Rogue armed with a dagger. Member of the archetypal adventuring band (Wizard, Rogue, Fighter, Cleric). Fighter engaged with a big bad guy, Wizard and Cleric casting spells and so on. Normal Rogue tactics, tumble in and make one sneak attack. Next round hope the bad guy doesn't kill you, sneak attack once and tumble away or, if you feel lucky, full sneak attack. Next round, if you've tumbled away, you are only going to get 1 sneak attack. If you didn't tumble away, you are probably bleeding on the floor.
-Vs-
Typical 12th level adventuring Rogue with Tumbling Pass and armed with a dagger. Member of the archetypal adventuring band (Wizard, Rogue, Fighter, Cleric). Fighter engaged with a big bad guy, Wizard and Cleric casting spells and so on. New Rogue tactics, tumble in and make one sneak attack. Next round, hope the bad guy doesn't kill you, then full sneak attack and tumble 10' away. If the bad guy follows you, the fighter gets an AoO and the enemy gets only one attack. If he doesn't follow you, the next round you tumble in, full sneak attack and then tumble back out to the same distance, gaining a great deal of damage immunity.
B) Typical 12th level Rogue armed with a dagger. Member of the archetypal adventuring band (Wizard, Rogue, Fighter, Cleric). His opponents are the same. Rogue wins initiative. Round one, he tumbles past the front line fighters and gets a single sneak attack against the Wizard. Wizard likely seriously injured. Remainder of round one, Rogue pounded into bloody mess.
-VS-
Typical 12th level Rogue armed with a dagger. Member of the archetypal adventuring band (Wizard, Rogue, Fighter, Cleric). His opponents are the same. Rogue wins initiative. Round one, he tumbles past the front line fighters and full sneak attacks the Wizard. Wizard DEAD, 95% guaranteed. Remainder of round one, Rogue pounded into bloody mess, but has a better chance of survival since the enemy wizard is too busy hemoraging to fight.
C) Hasting makes it much worse. Normal Rogue tumbles in 20', uses a full sneak attack and that's it. He's stuck til next round.
-VS-
Rogue tumbles in 20', uses a full sneak attack, then uses the partial action to do a normal 20' tumble away. Enemy has to chase him, losing any multiple attacks it might have. Rogue gains serious damage immunity.