I only have The Early Adventures, not the original Digest issues, so maybe I can't really help you, but here's my capsule description of The Early Adventuresnonetheless:
The adventures from the first four issues of The Travellers' Digest reformatted to 8.5 x 11 and MegaTraveller format (for characters, tasks, vehicles, etc.). Plus the subsector maps and Library Data from those issues*, deckplans for ships used in the adventures (the x-boat tender (recycled from Traders and Gunboats) and an original/new 300-ton liner), the Journalist career (in MT format), and equipment descriptions of various-TL recording devices.
The adventures themselves aren't particularly good (in fact, they're really pretty bad), so this book's primary lasting value comes from the Library Data, starmaps, deckplans, and Journalist career. AFAIK this book contains no material (aside from MT-format character and ship profiles) that wasn't in the original Digest issues, so if you already have those I can't see any reason why you'd need this too (especially considering the exorbitant price you'd probably have to pay for it).
*Trivia note: actually, only the Library Data for TD1-3 (covering Deneb and Corridor sectors) is included. The Vland sector Library Data from TD4 didn't resurface until Vilani & Vargr.