Normally when someone mentions Lightfoot's edition of the Apostolic Fathers they mean the 5-volume version. This is an abbreviated version, with just text and a few introductory notes. The Apostolic Fathers are represented primarily by one manuscript (yes, there are more for 1 and 2 Clement). As such, the Greek text for most of these has not undergone significant changes due to better texts being discovered in the last 100 years. There are certainly newer editions/translations of the Apostolic Fathers (e.g. the recent revision in the LCL series), but I like this edition. I find it easy to read. I recommend this for those who want to look a bit further past the New Testament into the early decades of the second century.