Here's his report with the things we already know and spoilers eliminated:
There's a whole new color scheme for the set. It still has the disco floor but now the lights make it look like they're sitting over a fire pit.
New 3D graphics for the displays. The HSer's display has a whole lot more stuff on it; the time remaining is shown as a bar that turns red when there are five seconds left.
The next person to go into the HS sits in the bleachers during the previous round.
The time didn't seem to bother most people. One person got down to just three seconds before using the PAF LL. After the time for the PAF expired, Meredith said, "Now you have just three seconds to answer." Then they started the 3 second clock. The HSer said, "X. blat, final answer" in time. That seemed to him like a little cheating.
Leftover time from the questions is available to be used on (only) the $1MM question.
This isn't really a spoiler because it will probably never make the air: