I was there, and it was a mob scene. We had the first, 10am group. They did let us in at 9:30, which was nice. Went right to MK, which was fine. But by the time we exited, the land was just packed. Most crowded I've seen it so far, way more so than the softs. At one point, the line for Toadstool Cafe went all the way back to the entrance pipe, I kid you not. The line for Toad, once you put your name it, still took forever because people were staying at tables forever, so no one else could be seated. It took about 90 min to do just three coin games, and about 2 hours to do all four coin games. Between the lines for games, rides, and Toad, all the lines started to intermix, so it was difficult to even tell what line was for what. Heck, there were even lines just to hit power up blocks and look through the binoculars on the 2nd floor.
Because of this, I think lots of last minute, spur of the moment decisions were made. I head by about 11am, Toadstool stopped taking reservations for a few hours. MK, which did have SR open, eventually closed it because it was nearly as long as the main queue time. Then they later started letting anyone play the Bowser Jr. game, because there was basically no way most people would have been able to earn the three coins and play the game (although I had also heard earlier in the day, they totally were not allowing that, so again, I think they were adjusting on the fly).
Really, IMO, this was just a matter of letting in too many people. I suppose it may be already too late for future AP previews, as the numbers are already set, but once the land officially opens, I'd hope they'd severely cut back on how many people can enter, and make use of that virtual queue with more reasonable numbers of people allowed inside. If they did that, I think it could easily be a different story.
And I do have to hand it to the cast members, who were trying their absolute best. T'wasn't their fault, and kudos to them.