This book collects the first 13 issues of the 24 issue first volume of Swamp Thing. The stories were all written by Len Wein with the first 10 illustrated by Bernie Wrightson and the rest by Nester Redondo.
While not in the same league as the later Alan Moore era, there is enough in these stories to keep a Swamp Thing fan entertained giving an introduction to a lot of the elements that Moore later reused for his own take on the character.
The remaining 11 issues in volume 1 have not been reissued in book form and having continued on from this book to read the single issues it is clear to see why. They are not of the same quality as the Wein stories and the writers don’t seem to have any clear idea what to do with the character.
So if you are interested in exploring the earliest roots of the Swamp Thing then this volume contains all you need.