As I read it, the vagueness referred to is not in the rules, but in their application in actual play - that is, without a grid it is not clear who is within 5', or 10', or whatever, of whom. Similarly, I think this is why the reviewer thinks that the cover rules create "more room for arguing". The arguments that are anticipated are arguments about who is how far from what.
This.
It happened in our Starter Set session. I told players to ignore the square grid and put their PCs where they wanted them to go. Since miniatures were all over the place, there were a few times where it was difficult to tell if a close miniature was actually an adjacent miniature.
In theater of the mind, this would be a nightmare for my group (especially between my wife and myself who can misinterpret each other merely from tone of voice
 ). I can totally understand how the reviewer could anticipate arguments within theater of the mind with 5E rules.
). I can totally understand how the reviewer could anticipate arguments within theater of the mind with 5E rules. 
				
 
 
		
 Granted, there are ways to alleviate some of that by using dry-erase markers and paper tokens rather then dungeon tiles and miniatures, so my example might be a tad extreme.  Guess it's my OCD kicking in, but if we're going to play with a grid and miniatures, well, time for me to bust out the paints and dungeon tiles!  I'm an all-or-nothing kind of guy, I guess
  Granted, there are ways to alleviate some of that by using dry-erase markers and paper tokens rather then dungeon tiles and miniatures, so my example might be a tad extreme.  Guess it's my OCD kicking in, but if we're going to play with a grid and miniatures, well, time for me to bust out the paints and dungeon tiles!  I'm an all-or-nothing kind of guy, I guess  
 
		
 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		