Very strong, Vertigo-Flavored debut
This is a debut issue that works on near all levels. It addresses that "things" in the DCU have recently changed, both overall and for Swamp Thing in particular. This helps the issue work for new readers who are unfamiliar with the specifics of the current DCU status quo, as well as being fairly unfamiliar with the character and world of Swamp Thing in particular. I'm a Marvel zombie born and bread picking this title up on the strength of writer Scott Snyder rather than any love for DC products or the Swamp Thing character, and I must say the issue works VERY well.
Not ultimately that much really happens in this issue, and much of what does is vague, but it still manages to rope you in. It is clear that Dr. Holland, who I gather has only recently become a separate entity from Swamp Thing, is readjusting to his humanity, and reevaluating his life's work. His explanation to Superman about how the world of plants is nowhere near as calm and serene as we think is a brilliant angle that casts the very concept of this character into darker light.
In addition, there is a horror element that starts building. What exactly is going on is far from clear, but it is presented in a very grim and outright harrowing way that is horrific and beautifully rendered at the same time. Artist Yanick Paquette has outdone himself. The horror elements of this book feel very much like old Doom Patrol from before the Vertigo label existed but was still on the cusp of a "mature readers" label; and that is VERY good company for this book to be keeping.