Iljitsch van Beijnum at Ars Technica compared the quality of iTunes 1080p downloads and Blu-ray:
I was surprised to see how close the iTunes 1080p download comes to Blu-ray, considering that it’s only a fraction of the file size. And let’s be honest: there are lots of Blu-ray titles that look much worse than this iTunes download. But despite an impressive effort by Apple, Blu-ray still reigns king when it comes to image quality. And unlike iTunes titles, BRDs can have uncompressed multi-channel audio, multiple audio language options, and special features. Am I being greedy in wanting both good-looking downloads for convenience, as well as buy-once-play-anywhere Blu-ray discs of my all-time favorite movies?
The future is digital, whether we like it or not. The quality of video compression will only go up. Not to mention the rising speed of Internet connections and size of storage drives, meaning we’ll have room for those massive Blu-ray-quality files.