Saw Age of Ultron today (which unfortunately coincided with some family emergency, but I'll try my best to not let it cloud my judgements). Overall I felt ambivalent. Spoilers ahead.
The good:
1) Action scenes were a step up compared with the last film, which was impressive in its own right. In my opinion the CGI was decent despite the fact that some shots of the main-villain, Ultron, looked inauthentic under certain light-conditions. Every member of the avengers got to show off his/her power sets. Hulk vs Hulkbuster simply blew me away.
2) Character interactions/drama also stepped up significantly from the last film. We got to explore the ghosts of several characters through flash-backs/forwards induced by Scarlet Witch's mind-control powers. The maincast was very-well fleshed out. I really enjoyed the party scene and some of the more indepth, introspective moments. You can tell how much Whedon loved his characters.
3) Dialogue, for the most part, was superb. Lots of fun quips and nods to Whedon's previous works (like Firefly).
4) One word -- Vision. I just loved what little I saw of him as a character. There were some child-like qualities about him that were ultimately overshadowed by innate wisdom. Could've been the perfect foil to Ultron if he were better written.
5) The fact that the Avengers showed concern for the civilians!
Now, the bad:
1) The villains weren't done well (what a surprise). Winter Soldier's end credit scene established Strucker as a threatening character but he was easily defeated in the opening and unceremoniously dispatched by the Maximoff twins just ten minutes later. My special criticisms are reserved for Ultron, though. He ended up being a complete let down despite being really threatening for the first half of the film. I felt that the fact that he quipped so much had a lot to do with it (will get to it later in the review).
Physically the Ultronbots were also a joke. Even "normals" like Hawkeye and Black Widow mowed them down by the dozens. The avengers almost felt like school bullies in the end fight. Felt really sorry for Ultron at the end.
2) The jokes. While most of them are great (I chuckled and most of the theatre were roaring), there are simply way too many of them interspersed in the action scenes.
3) Stakes were too low! Avengers get battered a bit but with the exception of Quicksilver, most of them felt invincible, even Black Widow and Hawkeye!
4) Plot was a mess by the time the movie progressed passed the half-way point. There were so many separate threads that you probably need a sixteen core computer to keep them straight. I felt that way, way too much attention was dedicated to foreshadowing future films than establishing character background.
Overall, a 7.2 out of 10 from me. I felt that it was a bit of a let down Marvel Studios knocked the ball out of the park with Winter Soldier, Guardians, and the new Netflix series.