At my EB, there were 300+ pre-orders, they were open later to let the most people come in and get the game to about 11 after allowing people to have it at 7. I had to send someone to pick mine up because of work, but they said that when they got there (around 10ish) the guys told that most of the 300 had been picked up already.

I was there today picking up the game book (it is cheap, like 16 without the preorder discount and they told me it was 400 pages) and there were only about 25 left. All preorders but if someone doesn't pick them in a day or so they will be sold first come first serve.
I got to play a little bit last night. It is a LOT bigger then any other GTA game. I think that Vice City could easily fit into one of the sections, and there are about 4-5 of those.
It plays a lot like the others, which is good because you can jump right in and know the controls and what the Waypoints mean. This one feels like it is stronger story wise, and the "RP factors" (not sure what to call them) add in a nice twist to the series. Makes it more like you are playing the person that lives in the city. *RP = buying clothes, building up your personal stats, side missions
I don't think anyone would play GTA infront of someone it would offend, but it is heavy with strong language, so you might want to watch who is around when you play.