I just got around to reading them. One thing that surprised me is the 2 meter rule is now optional and not to be enforced unless explicitly stated before the round. Also, they made it obvious that you can't stall by refusing to place your mini.
Here's a copy and paste of changes from the PDGA website:
Only one witness is required for a violation that results in a warning. Confirmation from a second person is required for a violation that results in a penalty throw. If a throw is subject to more than one violation, the one with the most severe penalty is applied. For example, a throw from an illegal stance that goes OB is penalized for being OB. Ties are broken by chronological order of the violations. For example, a throw that goes OB and then crosses the wrong side of a mandatory is OB.
The 30-second clock (excessive time) now starts when you reach your disc, rather than after you mark it, since a disc may not be marked. You can no longer stand over your disc holding your mini for an indefinite amount of time.
Carrying an illegal disc is no longer punishable by itself. You have to throw it for there to be a penalty. The same goes for an illegal device. You are allowed to use a towel or pad on a lie. GPS devices are no longer disallowed.
"The thrown disc establishes a position where it first comes to rest." That is an important concept which provides a basis for many other rules. Once a position has been established, it remains even if the disc moves, no matter how that happens. The following rules are now related to establishing position: disc above/below ground, broken disc, and disc in water or foliage.
The disc on the playing surface is now the primary way to mark the lie. The use of a mini is presented as an alternative.
The thrower cannot call or second a stance violation. That closes the self-called falling putt loophole. You are now allowed to retrieve a disc after a stance violation (the excessive time rule still applies of course). There is no longer a three-second limit on calling a stance violation. All calls must be made promptly, as noted in "Application of the Rules".
A few exemptions have been added to the interference rules: interference to prevent injury or to prevent (with the thrower's consent) a disc from becoming lost is allowed.
The two-meter rule has been moved to "Discretionary Rules".
"Playing from Another Player's Lie" is now an "Incorrect Lie" misplay, meaning there's just one penalty throw instead of two. The player whose disc was moved handles it the same as the disc being moved for any other reason, and replaces it to its approximate position.
The entire group must assist in the search for a lost disc. Whoever starts the clock has to tell the group that it has started.
You can no longer throw back across a mandatory line after having made the mandatory. There's no longer a default drop zone. If the Director has not designated a drop zone, go to the previous lie.
A scorecard is late after 30 rather than 25 minutes.
Disc Golf (n): A game in which a round plastic object is thrown into trees until it is beat in to resemble its preferred flight characteristics, at which point it is thrown into a lake.