8.4.1 Does the active player also get a chance to respond?
9.4 "Any face down card in the card pool will be placed in the discard pile." Does this also apply to face-down cards that are attacks or copies of other attacks, like those generated by Come to the Aid or You're Not My Father? If so, it's a reversal of previous rulings, and I like its simplicity.
If this makes an exception for those attacks, then I'm confused. In my mind, "face-down" or "face-up" are like ready and committed. You're either one or the other. And a face-down card turned into an attack is still a face-down card. (In the same way that printed values can never change.)
9.8.1 "If the attack has generated a vitality loss of one or more to the opponent during the Damage Step, it may instead be placed in the momentum." This means that Dash Uppercut (original) and Burning Knuckle no longer get to go to momentum after being played as blocks, since they do damage at the end of the Block Step (not during the Damage Step). This simplifies things, and I like it.
10.2 "from the game, he loses the game." should possibly be "from the game, that player loses the game." to be consistent with 10.1 just above.
10.3 This is not a complete sentence. It should probably read, "If a card effect specifically states that a player has won the game (e.g., Close to the Edge, Soul Hive), then that player wins the game." It doesn't technically need to be a complete sentence, since section 10 starts with "The game ends immediately if any of the following occurs:" But since 10.1 and 10.2 are both complete sentences, 10.3 stands out as odd.
12 Form. If you are moving away from the old Form terminology, then the Form definition might need revising.
12 Penalty. The phrase "negative subtraction" is silly (I know it's from the old TR). "negative modification" would be a much clearer phrase, as it doesn't get into issues of -(-2) = +2.
12 Ready. "straight up and down, also" should be "straight up and down; also," to be clear that these are two separate definitions.
12 Sideboard. You've already noted that this should be removed and added to Tourney Rules (forthcoming). Just noting it here for completeness.
12 Unblockable. Any tweaks made to how unblockable works should go here.
12 You Own. "in your deck and sideboard." should probably be changed to "in your deck." For the purposes of game play, the sideboard doesn't exist.
This concludes my first review. It's by far the best Rules document UFS has had so far. Many thanks, Antigoth. Additional thanks to James, Tag, and Gou for their contributions.
Additional thanks to Aslum, Cetonis, Nyobari, Baranor, and anyone else I'm forgetting who contributed to the editing/review process.