Panned is a strong word, I think. The uncut 181-minute version was released initially and the reviews for it were out of this world, it was weeks later when exhibitors complained that they couldn't cram enough showings into a day that Jack Warner decided to take an axe to it. Critics presumably knew what the deal was, the public definitely must have felt cheated. The most despicable part of the whole thing is that WB didn't even care to put those cut 27 minutes into their vaults for posterity or anything, or preserve the master print in its original length. They just instructed theaters to destroy it. Thank god not all of them did and we at least got ~20 minutes of footage and all the audio restored. I still hope the complete version will resurface someday, there've been rumblings that it exists in a private collection.
It's an incredible movie, if not in my top 10 of all time then just outside.