RDJ nails the part of Tony Stark imo, especially if you've read Ironman back in the early days. Whether RDJ drew from his own personal experiences or not to bring this comic character to life is irrelevant,as long as he got it right is the most important thing. IMO, RDJ gave the single greatest performance as the character lead in a superhero movie, even more so than Bale as Bruce Wayne.
I think 8blades isn't able to understand the concept, that a film can be both fun and SERIOUS at the same time, which is what IM was. IM was one of the few superhero films to actually touch upon real-world issues that are happening right now. US soldiers fighting and dying on foreign soil, terrorism, WMDs vs. the the social responsibility and conscience of corporations, contrasting with corporate greed that allows the excessive proliferation and manufacture of weapons simply for nothing more than profit. THAT'S SERIOUS. IM doesn't take place in a fantasy city called Gotham where everything happens within the containment of that sole environment. IM takes place with the background of actual events. That's serious. IM/Tony Stark took personal responsibility to take the weapons out of the "wrong" hands and wasn't afraid to cross lines or "pull the trigger" in order to do this. That's SERIOUS.
Sure, IM had some humorous moments but if you thought it had an "overall comedic" feel to it, then you weren't watching the same IM movie that I saw. And that's not even getting into all the scenes of torture Tony and Yen sen endured during captivity as well as all the boozing and womanizing before his epiphany.
But to each his own though. Oh yeah, I liked BB but it wasn't the holy grail of superhero films that some make it out to be either. Trust me, it had it's flaws too.