Just got back.
I thought it was a good deal better than the first Avengers film. Whedon's direction was actually leagues above his previous outing, so well done to him. I also appreciated that while the plot was convoluted at times, that this film - unlike the previous film, took the time to actually develop the individual characters and their relationships with each other in a way that didn't feel perfunctory.
ILM's work was outstanding.
Ultron was a huge letdown of a villain, though. Talk about muddled motivation. Also, any sense of intimidation or threat he starts with is quickly undermined and evaporated as he turns into just another forgettable, light-hearted butt of a joke, saturday-morning cartoon villain.
So colour me surprised. I was expecting a film on par with the middling first one and got something better.
Whedon's script could do with a little more economical use of screentime, but what's there is much better than the first film.
3D was pretty much worthless outside of adding depth in the in-helmet close ups of Tony and his HUD.
TWS > AoU > IM1 >>> >>> etc