Just worth noting for those thinking of swapping existing DVDs / Blu Rays for this collection.
In the case of the two Iron Man movies, on both DVD and Blu Ray these were released originally as 2 disc editions. What is in this set is the first disc from the the Blu Rays of each movie. So you'll lose out on any special features on the second disc. Note anything on disc 2 of the DVD sets hasn't been including on the Blu Ray.
For the Incredible Hulk, all the features of the two disc DVD edition are on the single Blu ray disc in this pack.
Captain America and Thor are as the original Blu Ray releases.
Avengers (Assemble) is the standard Blu Ray also.