Re: IM3 a "continuation" of the previous movies good idea or horrible?
I don't see a problem. The existence of the Avengers inherently changes Iron Man's world. Thus, you can't ignore it. Why try and ignore it? I don't think they'll overload the film and not make it about Iron Man, but at the same time, many new possibilities are opened up with the Avengers being around. The movie shouldn't be chalk full of cameos, but like the comics, now that Captain America exists in the world of Iron Man, you have to explain why Iron Man decides to fight Mandarin alone as opposed to just bringing Cap, Thor, etc. These need explained, and you need a plan. You can't just isolate the Avengers from Iron Man's world after the Avengers form. Like it or not, they become supporting characters in that world, and you have to account for them.
I agree with Marvel on this.