Okay, the reason I have absolutely no beef with Tony's PTSD? Up until the events of "The Avengers", every threat he's fought has had a terrestrial origin. These are familiar to him, he was an arms dealer, he understands human nature and the business of war. Those are the sort of threats he feels comfortable neutralizing. He's aware aliens exist, he knows of Thor (and doesn't seem to like the idea of him very much), but had never actually encountered anything not of this Earth. Now, he's battling an ARMY of evil aliens intent on destroying/enslaving humanity, then has to go through a wormhole, sees what's on the other side and nearly dies in the process. His entire world-view has just been shaken to the core; this isn't just that his life had been in danger, this is taking his entire notion of reality and tipping it on it's head. He's doubting his ability to keep the woman he loves and his entire WORLD safe from a universe that just suddenly got a lot bigger and a whole lot more hostile. I think PTSD in that context is entirely believable, very human, and the fact that he muscled through to the other side of it actually makes him seem more heroic, not less. I still didn't care for a lot of things in IM3 and feel like it's a flawed flick, but Tony's panic attacks didn't bother me at all.
