I can wax eloquent about the glory that is FW, and how different modern game culture would look if Old School play followed this branch rather than the D&D branch.
I love this so hard I sought out the traditional RPG sized hardcover a few years ago in addition to the SFBC edition we played back in the day.
My very first 3 historical campaigns were played using these rules; although, alas, none lasted nearly as long as our AD&D campaign.