A lot of wasted time and potential. Worth watching just to appreciate that Joss Whedon is doing the Avengers.

Rating: 3/10 (3 September 2013)

==++++SPOILERS++++==
Nothing can compare to the sheer anger I felt after Stark came face to face with the Mandarin for the first time. I mean, up until then the movie wasn't bad, although it did feel as though the pacing was a bit rushed at times and there were too many quick jokes for my liking. But then it really started to feel like the director hadn't actually watched the other films, nor read an Iron Man comic in his life. I could deal with pretty much every little plot hole or poorly written bit of dialogue up until they decided to turn Tony Stark's greatest and most powerful enemy into a drunk British actor called 'Trevor'. I just kept sitting there thinking 'oh, I see, the Mandarin's obviously added a decoy to throw people off, that totally makes sense' and even enjoyed the comic relief that character brought, but if a movie has to explain why, suddenly, the Mandarin isn't the main villain 3 TIMES over the course of the film, making up about 20 minutes of total screen time too, none the less, then something has gone incredibly wrong.
Not only did the Mandarin get destroyed beyond repair, but the rest of the film after that made little to no sense at all either. I watched the trailer expecting a big showdown with Mandarin, or even just to know he's made an appearance then faded into the background to pull the strings, Sherlock Holmes 'Moriarty' style but no. Instead I get treated to a wonderful 40 minutes or so of build up for a lazy, and incredibly poor joke that gives me a headache just thinking about it. After Black was done with screwing over one of the most feared characters Stark has ever met (He has ten alien rings of power and an alien DRAGON to help him out at times. Seriously, look up 'Fin Fang Foom' ) he transformed what should have been a great film into, essentially, Lethal Weapon all over again. From the handgun firefights through to the actual Villain being one dimensional and incredibly boring, the whole film felt like it could have been added as extra scenes into 'The Last Action Hero' from the 90s.
Also, this is a lot more than simple comic book 'herpyderp, they mucked up my favorite character!' that fuels of lot of nerd rage, but is more to do with the trailer too. I honestly felt I've been mislead by watching that. In the trailer, it shows the mandarin to be the huge bad guy that's been playing behind the scenes, and shows him to be just what he is - a powerful, scary individual who is easily a match for Stark in every way shape and form. Its one thing to have a plot twist and change the antagonist halfway through the story, but to advertise and market the WHOLE film about him, not to mention connecting both other films to him too (eg. - the 'Ten Rings' organization in the first film), build him up to be exactly what he's supposed to be and then replace him with a simple one dimensional 'villain with a grudge' is by far the worst thing they could have done.
I'm offended not just as a marvel fan, but as a general moviegoer too. This could have been so much better, and words can't really describe how disappointed I am after watching this.