When Avengers: Age of Ultron first came out, many complained that the film felt "rushed" or that characters were not sufficiently developed. There was talk at the time of a "director's cut" or extended edition forthcoming on disc that might remedy this. Unfortunately, Joss Whedon squashed that when he burned out on the MCU and decided he was done with it. It probably wasn't going to happen anyway, as Marvel has not yet made an official extended edition of an MCU film.
samspider3 steps up and remedies this, to an extent. If you've seen any of his previous fanedits, you know that his skills as an editor are top of the line, and that excellence continues in his A:AoU fanedit. Edits are seamless, music cues perfect, dialog crisp. The HD presentation looked awesome on my 55" Samsung. With the exception of one scene, which I'll touch on later, it's as good as it gets.
If you read my review of samspider3's Marvel's The Avengers fanedit, you'll recall that I did not feel that the added scenes helped the movie. The exact opposite is the case here. The scenes added allow the movie a little breathing space, and give the characters some extra moments that help them build. In particular, the restored Thor/cave scene and the following scene where Thor wakes up Vision are vital to the narrative. So many people came out of the movie wondering what the heck Thor was doing; having these scenes reintegrated explains it all. The buzz was that the studio told Whedon to either cut the farm scene or the cave scene; Whedon chose the latter. But in the end both scenes are necessary.
The one scene that misses the mark a bit is a scene where Cap is talking to Maria Hill after Ultron's initial attack on Avengers Tower. The scene was unfinished, and the back of the stage and green screens are visible and distracting. Perhaps copying a background from a finished scene would help here (if possible) or just darkening the background so it's not as obvious. Or just leave it out; it's not as critical of a scene as the Norn cave.
All in all, this is now my go-to version of Avengers: Age of Ultron. The extra character moments are just what the film needed.