I didn't like Dream Dark. 
 ***** 
 Dream Dark is not necessary. I mean, Garcia & Stohl could've incorporated Link's story piece by piece in the succeeding books. Still, reading it brings me back to the dark and eerie Caster World. Is it essential to read it before Beautiful Chaos? I think that's a NO. 
 I like Link, I even like him more than Ethan, but Link's character was not highlighted that much, considering this e-novella is about him. 
 You can skip reading Dream Dark. It gives you nothing than what you already know about the Caster Chronicle Series (well, if you read books 1 & 2, that is).