The more I think about it the more I like it, though I did find it extremely incongruous that there was next to no SHIELD presence in the movie, other than a few dialogue hand-waves. And other than the easter egg at the end there was no one else from Avengers there.

I was saying to my friend I thought the voice-over narrator was a cop-out until it was explained by the easter egg. That paid off, at least.

I'm still marshalling my thinky thoughts, but I have at least two reasons so far for why SHIELD aren't around:

1) The Mandarin is specifically a US problem, one that Rhodes says he's not even meant to share with Tony. It's antagonism directed at the US President and the US, with Iron Patriot, is meant to be dealing with it. Not any Avengers. And so not SHIELD. You have to ask how much involvement SHIELD has, if it only comes in for the international things, or the espionage where you don't see them, or aliens from outter space. But as it stands, if the President doesn't want the Avengers, not even just Iron Man, then I doubt he and his command team want SHIELD involved either.

2) Why SHIELD don't help Tony. Well, from Happy getting hurt, to Tony declaring his address, to the attack on Malibu, to Tony going off grid as presumed dead and with JARVIS down, and Pepper going off grid with Maya, is actually a really short timeline as far as I can work out. Unless Tony stepped in and asked for help, which he didn't, I think SHIELD would assume the guy that consults for them and faced aliens can handle himself. Add to that Tony's attitude in the past when help shows up that he didn't ask for. So by the time his house explodes and he's presumed dead then they can't get in touch with him anyway.

...3) on top of it's Christmas time, and SHIELD are probably still recovering from the attack on New York themselves, and we don't know what the MCU timeline is looking like, whether they're elsewhere dealing with something we'll see on Thor 2 or Cap 2. (And, of course, the filming reasons, like having these films focussed on individuals rather than dragging in multiple characters, and how the plot would change with SHIELD involvement.)

For the Avengers I think maybe they're all off recovering, or doing whatever in Cap 2 or Thor 2, again we don't know what's happening in the wider timeline thing. And if Tony is living in Malibu then the Tower is either not repaired enough to live in and/or with Tony not wanting to be in New York at the moment with his anxiety, the others couldn't live their either and/or may want to get away as well. But then there's Bruce at the end, and mentions of superfriends from Happy, so we know they're still somewhat in touch with each other. I'd be happy to wait until Avengers 2 for them to get more comfortable with each other :)

I LOVE the extra credits seen. Me and the people I went with laughed ourselves silly :D