When comparing several well known AA prints of certain negatives made in different decades, it's evident that his aesthetic evolved over time to amplify "impact and interest" to some extent over "technical perfection"* whatever that is. John Szarkowski includes a number of these photographs in "Ansel Adams at 100", and the differences are dramatic with nearly featureless dark areas that were open and detailed in earlier prints. "Moonrise" itself evolved that way, and the last prints are emphatically so. To ask if it's a 'great' photograph is to wonder why the woman I think is beautiful is unattractive to you. Kinda pointless....
*For me, technical perfection is what occurs when I have made a print that exactly meets the goals I set for it.
I don't think that is exactly what jovo meant. Technical perfection being a print that satisfies the photographer and achieves the desired aesthetic for the image. And this is not something absolute or static. It can evolve over time.
As for Adams, yes his prints - particularly from the late 60s onward and characteristic of the 70s - are more "dramatic" than his earlier versions. He himself acknowledged this using the term Wagnerian.
I don't know why it's a good photo, but for me it's very important photograph.
Without that picture I'd shoot still digital. When I first saw it, it was a shocking experience.
I had the privilege of seeing a print of both Moonrise over Hernandez and the clearing winter storm in Yosemite in person as part of the "Western Exposure" exhibit. Truly amazing to see in person, though I preferred the clearing winter storm print. Interestingly enough there was another photograph he made not far from the clearing winter storm photo (I forget the name). The positions were remarkably similar, right down to the two tall trees in the lower right corner of the photograph.
Western Exposure also showed some of his color work, but most was B&W. If you get the chance to see Western Exposure, do so. You won't regret it.