The six issue mini-series was collected in paperback at the start of the 1990s, just a half dozen or so years after the actual story.
Along with the straightforward reprinting of the individual issues, it has an introduction by editor Mike Gold that builds on the text pieces in issues #1 and #2. At the back of the book, it has four pages used to display the covers of the crossover issues along with the three new series (JUSTICE LEAGUE, SUICIDE SQUAD, and FLASH) and the COSMIC BOY mini-series that launched straight from LEGENDS itself.
In 2016, a new collection was issued which featured a recoloured version of issue #6’s cover, boldly emblazoned with the line “Featuring the Suicide Squad’s 1st Appearance!” It seems likely that the release of the Suicide Squad film in 2016 probably contributed to the release of the new 30th Anniversary Edition, hence the tag line on the cover.
The collection itself has refreshed colours throughout but apart from that, there’s nothing much more in here; even the Afterword is actually the same Introduction from Mike Gold mentioned above – they’ve simply moved it to the end of the book.