Halo Reach is going to be a Beast. Microsoft and Bungie are going all out with the three different game package offerings plus the newly announced Halo Reach edition 360s (I wish I had waited to upgrade). With the new Firefight versus mode and Forge World from Comic Con, this is what Halo REach content will include so far:
Up to 4 player co-op, Multiplayer including all the variants and customization, Firefight (includes score attack, versus, grunt party, and customizible games), Forge World, Film clips, screenshots, etc.
It's going to be huge and I do not see another first person shooter with as much content in the near future....the only thing I have not seen mention is will the single player have the metagame scoring option from Halo 3.
I can see that US preorders coming close to 1.5 mill with first day sales WW around 2.5 to 3 mill.