I am trying to remember if there was a CE film that I did think was a waste of my time. Not that I would regard many as the greatest ever, except maybe in a cult sense.
Of his Westerns, "The Outlaw Josie Wales" would be my top, I found Unforgiven just a bit too relentlessly dark so it gets pipped. Of his recent films, I think "Letters From Iwo Jima" to be the best of the that bunch. Maybe it's the relative novelty of the subject and viewpoint that gets my attention. Whether it accurately portrays the Japanese viewpoint as opposed to the their circumstances is another question, but I figure he did a very decent job. I cannot with hand on heart say it was better than "Flags...", but I did find LfIJ much more interesting, not that I did not enjoy FooF.