I thought it was a really good first issue. I liked how Tynion showed off DC's magical side as considering themselves different from the "capes". I loved how Constantine made his first appearance. I feel like Tynion has a good handle on each character's voice and manages to make them all sound different. I'm a bit iffy on the Zatanna redesign, I prefer her classic costume.
Also man this comic got pretty graphic with the body horror, moreso than I'd expect for a non-Vertigo book.