Initiative: Since both quick thinking and quick movement contribute to initiative, both Dexterity and Intelligence will now contribute to initiative bonuses.
Stat Increases: Stat increases will now use the 4th Ed schedule: +1 to two stats at every level ending with 4 or 8, and +1 to all at 11th and 21st.
Feat swapping at levels: You may swap out one feat that you rarely use when you go up a level.
Movement: Diagonals count as a single square. Players may move freely through other player's squares provided they do not end their turn there.
Turn Structure: Turns consist of Free, Move, and Standard actions. Full attacks take a full round, but Free actions may be taken at any time, even out of initiative.
Marking: Fighters will be able to mark anyone within range of their melee weapon, one person at a time. Movement or attack against anyone other than the fighter gives the fighter an attack of opportunity. If the fighter hits, movement is stopped, attacks are made at -2, and casters must make a concentration check to get the spell off.
Attack Of Opportunity with Shield: If a character uses a shield for an attack of opportunity, a successful hit stops the opponent in their tracks.
Ritual Casting: A wizard may cast a spell directly out of his or her spell book even if the spell is not prepared for that day, taking one minute per level of the spell. This cannot be done under threat; noisy or distracting environments will require one concentration check per minute.
Spell Save DC Enhancements: Casters now add +1 for every 4 levels to the save DC for all spells. There are also now Wands, Globes, Daggers, etc which will add to your spell save DC, but these are VERY rare, artifact rank items.
Passive Perception and Insight: Players have a chance to notice something without rolling. Passive checks are used to avoid notifying the players that there is something to check.
Tactics Skill: Fighters and Paladins gain the Tactics skill as a class skill, which gives them a chance to identify the most dangerous opponent, spot ambush situations, and figure out where the greatest threat is likely to be.
Encumbrance: According to the current encumbrance rules, a person of average strength would not be able to walk down the street at a normal pace wearing winter clothes and carrying a bag of groceries. This is ridiculous. Clothing, armor, and items carried on your belt that way less than 5 lbs only contribute half of their weight to encumbrance. Items carried in your hands or strapped to your back contribute full encumbrance.
Bonus Cantrips: All casters gain one bonus 0 level spell for each bonus spell of any level that their main stat entitles them to, when they reach a level capable of using the bonus spell.
Weapon Specializations: Weapons will be grouped together for weapons specialization, rather than being a single weapon, as in the D20SRD
Castling: Two characters within movement range of each other may exchange places on whichever initiative comes last, provided that neither move beforehand.
Druidic Shapeshifting: In the Pathfinder rules, Druids keep their own stats when shape shifting, plus a bonus. This leads to the absurdity of creatures that are not even strong enough to breath, let alone stand up. When Wizards cast the spells given as reference points, they gain the bonuses described, and so they have to be careful, but Druids gain the full strength of the creature, regardless of their own strength. This is the advantage of being a Druid. Druids are limited only by the type and size of creature, but cannot assume the form of a creature whose CR is higher than their level.
Open Ended Rules: The problem with adhering tightly to the rule system is that everything the rules do not expressly permit, they prohibit (this is my main objection to rules lawyering--it becomes a straight-jacket for the players.) If you want to do something that is not covered in the rules, say what you want to do, and I'll work out a probability. You could trip someone with your staff, throw sand in his eyes, bluff him into giving you a flat footed attach, knock him back over a step, etc. There are many things that you can do that are not in the rules.