Never heard anyone say that about Superman Returns, it was a beautiful look, most people criticized the film for whatever shortcomings they thought it had, but as far as it looking any different than 35mm film, it didn't. It's a great example of how you can make digital look cinematic.
Then you likely didn't read very many reviews or ask many opinions. If anything, the look of that picture was heavily criticized, and even more so on the video release, which was very artifact laden and had many odd color effects as well. Personally, I didn't mind it, and Tom Sigel happens to be an old friend, but my opinion seemed to be in the minority.