a quarter of a billion dollars to make,almost 2.5hrs long....for this?

Story goes Stark & Banner try to make a program to protect mankind, but cant. but then while they are out having a drink it magically happens by itself (never explained how).. It then becomes self aware (like Skynet) & decides to wipe out humanity (again never explained why) & goes to live in the internet (maybe while there it watched Thor or two girls one cup & decided to end us), magically making armies of Iron men-a-likes from who knows where (again no one explains why there's iron man factories all over the world to borrow). He keeps turning up now & then & the avengers keep killing them & him. though the avengers also destroy pretty much all the buildings in the various cities they turn up in (bit like team America) but also spend all their time trying to save all the humans in said cities as well (which becomes unintentionally hilarious considering the destruction the Avengers cause) well, that's the story....if you think that'll keep you engaged for nearly 2.5hrs you might enjoy it. the computer graphic effects are generally very good , 3D isn't great.