I used to be a huge fan of gallery walls. Emphasis on used to be. (Past tense.)

That is until I came to the realization that I just can't pull them off properly.  

Gallery walls have to be precisely executed to look polished.  Otherwise your wall can end up looking like a hot mess! Trust me, I know from personal experience. I just took down my own gallery wall because I gave up on trying to make it something it will never be.  Crème brûlée can never be Jell-O (and vice versa).