Whedon is, as usual, witty, enlightening, self-deprecating, insightful, and just plain entertaining in a "let's talk about this movie with my friends" way.

Whedon admits that the Hawkeye character was left in the dust as "he had too many characters to deal with". He gives some honest truths about 3D conversion versus native 3D talking about loosing hours over a single shot. Because of the star power of the cast he was afraid to give them direction. The previous movies are both a gift (the quality of talent) and a hindrance (sticking to story continuity). Admitted they went with the Bill Bixby version of Banner. He uses the word specificity a lot. Writes to soundtracks (such as Hart's War and Star Trek). His idea for the Harry Dean Stanton scene was that Banner had fallen into a Coen brothers movie. Considers the first Terminator movie and The Abyss important inspirations and seminal. Several times Joss threw lines to Downey Jr (such as Shakespeare in the park and the Shawarma) and he ran with it and built on it. The central park scene was done with no sound as there was a huge mob around them.
In other words, this is a typically excellent and funny Joss Whedon commentary. 8/10

This is actually a commentary for Age Of Ultron which doesn't seem to be on here. A typically solid Joss commentary that covers all bases but just gives you enough to realize what a challenging film this must have been both mentally and physically. He talk covers the gamut from production logistics (working with the Cultural Minister in Seoul for example) to editorial changes (he often refers to the DVD deleted scenes) to technical choices (the visual style is completely different to the first film). Although there are no real Eureka moments to really explain what happened on this contentious production, the following three quotes really sum up this commentary for me:
"this film was a series of compromises and failures" directly followed by "I'm talking to my shrink about it" :). And "Chris Towsend oversaw 97 effects houses".

Definitely an informative commentary.

I'm usually hesitant to listen to commentaries when it's just a single filmmaker (more opportunity for dead air), but Joss manages to fill the vast majority of the movie with amusing annecdotes, tidbits of information and a surprising (and almost off-putting) amount of self-deprication. I recall him going on for over a minute while he rambles on about an analogy of the crumbling SHIELD facility and how making a film is similar in that regard ("the ground crumbles beneath you and you're barely able to keep ahead of it") and how he was fumbling to keep up with it. It was funny at first, but the longer he went on, the more awkward it was to listen to because he kept undermining himself in an attempt to be funny.

The other turn-off about this commentary is just how much of it is Joss saying "This is cool", "that's cool", "that was so cool", "that was fun". (Spoiler Alert: It's a lot.)

FUN FACTS:

-He believes that post-conversion 3D can look better than true 3D. He spent 3.5 hours of a 12 hour day shooting the end-tag of "Thor" because he was dealing with this massive, cumbersome 3D camera, so he basically said to himself "never again".

-The inclusion of Pepper was Robert Downey Jr.'s idea.

-He originally wanted a second villain in the movie because he didn't feel Loki could carry the movie at first.

-The battle between Iron Man and Thor was a Marvel Studios decision from the start. Kind of a "You WILL do this in the movie!"-command.

-Admits that he's not proud of the "Phantom Menace"-esque ending with the Chitauri, but it was necessary to deal with them in such a way.