Yes, I've seen it. It's got an interesting premise, and if you like Leone's other westerns, then you'll like this one.
Sergio Leone was indeed a great director, but Leone had a real weakness in terms of editing, in my opinion, and his movies often move slowly as a result. I can only guess that movie studios would re-edit his films without his permission, because the 'Director's cut' of (for instance) The Good, the Bad, and the Ugly (one of my personal favorites) is about 30 minutes longer than the studio cut, and the studio cut is still almost three hours.
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