I liked Captain America, but the pacing of the film seemed off, especially the second half. The ending was too abrupt, and the whole thing seemed more like a prelude to the Avengers than as a stand alone film.
I agree that ANH is kinda underwhelming, but more in terms of color timing. As for detail, I was surprised by the amount of detail on R2 & 3PO. The scratches and dings on their bodies are apparant, which is a contrast to their pristine appearance in the PT.
ESB however, looks incredible. The picture is crisp and detailed while keeping a filmlike appearance. Other than Vader's pink lightsaber, it's the best it's ever looked on home video.
Regarding ROTS' audio. I thought that the bass in TPM and AOTC was way over the top, the humming of the lightsabers was way too much. OTOH, the OT lightsabers did not have that much LFE. I would say that ROTS conforms more with the OT audiowise. There was one scene where the lightsaber has deep bass and that was Vader igniting his saber before he slaughters the younglings, that can be seen as a creative decision, to make the scene more menacing.
I also have to agree that the dialogue in Thor is mixed too low, as opposed to X-Men first class. In Thor, I had to turn the volume up when hearing quiet conversations, and then quickly turn it back down when the fight scenes and explosions occur.
Call me crazy but IMHO, Spielberg disavowing the SE of ET shows less integrity as an artist and more like a salesman, willing to kowtow to his consumers whims if they disapprove of his filmmaking decisions.