On the characters, they have been more fleshed out since the first Avengers and are about as good as they were before. Interactions and banter is good, there is a bit of a forced romance which does not work super well and Hawkeye of everyone probably gets the best character development and the best line in the movie. The new additions are a bit underwhelming, Scarlet Witch and Quick Silver have their moments, they don’t get a ton of dialogue which is a guess for the best considering their fake Russian/eastern European accents. Visision on the other hand is very good, his initial appearance is great and Paul Bettany got pretty lucky. Quite a few other MCU characters pop up in the movie and its good seeing them, War Machine gets a slightly bigger role than you would think, Falcon not so much.
Ultron is mostly good, he sound amazing and looks amazing save for his mouth movements which were a bit off for me but that’s knit picking. The main issue I had with him is the flip flopping he goes through being very menacing to a bit too comical. He is supposed to be of Tony Stark and his displeasure at being compared to Stark is funny but it also feels out of place at times. If I could pin point it Ultron lacks charisma, he's says the right things but I don’t think he inspires much confidence.
As for the MCU in general, there is some interesting Thor Ragnarok stuff that sets the scene for Thor Ragnarok. The stage is set for Captain America Civil war but nothing directly leading in. Not really any mention of Ant Man unlike Winter Soldier, No Spider Man hints either. There is some Phase 3 strings but too much aside from the Thor related stuff and a Dream Sequence.
On the Subject of 3D don’t see this in 3D, I don’t know if it was because of lack of sleep since I had gone out the previous night but when I saw it for the first time the 3D was pretty subpar, passable in most cases but definitely made the movie worse. When I saw it regular it was a lot better, motion was better as as expected colours were a lot better.
Overall Avengers Age of Ultron is not a bad film, its pretty good actually but it does not have the impact of the original. Everything is technically bigger and some would say better but there are also times when it feels like its going through the motions. The story of Ultron and the evolution of the characters is fine and everything but with Thanos on the horizon Age of Ultron feels a bit like a warm up for Phase 3 than the culmination of everything Phase 2.