He entered his draft year with people expecting him to be better than Ekblad. Only other D with his tools to enter the draft in recent years is probably Seth Jones. Ekblad was viewed as not being as good a skaters, and Hanifin offensive upside was questioned.
He has absolutely ridiculous tools, he was a man-child with elite skating. In his draft year, he seemed to force things and consistently skated himself into positions with no options. This put him out of position and caused turnovers. Now, at the junior level his skating was at an elite enough level he could recover, at the pro-level it was unlikely. It seems at the NHL level he has started simplified his game, and play the game he should be playing. I'm not sure if not having him back in junior so he could refine his offensive approach wouldn't have been better, but it will be interesting to see how he turns out. In general, I don't really like having 18 year defenders (even teenagers in general) in the NHL, especially ones out of the CHL. Granted, this year we have an interesting wave of good ones (Provorov, Werenski and Chychrun).