How does this compare to the Patagonia R2?

I agree with Brandon about the bath mat look.This is a very thin but warm fleece that I ended up wearing over and over because of it's warmth to weight ratio.I own almost every fleece Arc'teryx makes,and aside from the Apache AR,this is my favorite for fall by itself and in the winter under my Alpha SV jacket.

the Delta AR zip will offer similar warmth when worn under a shell. It's probably slightly bigger when packed. Either top will offer the same amount of weather protection when worn alone, which is to say, not much. With the Delta AR you don't look like a walking bath mat.