I’ve been to three of these events and have enjoyed them. Basically, MGM is filled with the characters roaming around, and there are a few comedy sketches, quiz shows, and interviews with some of the celebrities from the movies.
The days that I have gone, it has been very, very crowded. In fact, in 2000, it was the most crowded I had ever seen MGM (I have video of this). In 2001, the crowds were a little lighter the weekend I went, but I saw subsequent photos in which crowds grew depending on the guests. Don’t get me wrong- you can still do and see everything - it’s just a lot of people.
Last year, I encountered a lot of crowds on Saturday, but by Sunday, it was a lot easier to get around. It really probably depends on the guests.
This year, with the celebration of the parks going on,as well as the advent of the new movie, it’s bound to be busy.
But actually, unless there is something that you absolutely MUST do, it’s actually better when it’s busy.
Hope that helps.