Without a question its impressive. People are letting their dislike for it cloud rational judgement. Not many games at all, single or multi, have as high a completion percentage. The very mention of the game seems to turn their brains into rocks.Any person who boots up a game just once gets added to the "incomplete" list. Rentals, borrowing, and even just plain quitting at any point all affect completion rate.
For example, the very first boss in Dark Souls III, who you encounter about 30 seconds into the game, has a trophy tied to beating him. Currently that trophy has been unlocked by only 87% of players, and that's just the first few minutes of the game turning away 13% of all players. I haven't even completed Dark Souls III (although it's on the list...that fucking ever growing list). Less people (myself included...and obviously percentage wise) have defeated the Deacons of the Deep than have completed The Last of Us. I'm aware Dark Souls has an overall high attrition rate, but their achievement lists make it incredibly easy to track where people stop progressing.
With that said, I personally see 58% as a VERY impressive completion rate number, no matter the game. But I also don't see why it even actually matters at all.