This is my all-time favorite LEGO set. Period. Now you know.
The Forestmen were my favorite faction, and as a mid-sized set, this included enough minifigs that my Robin Hood fantasies could be realized. In addition to the minifigs themselves, it had full plume wheels ("sprues") in three different colors, with a horse, basket, two goblets (unusual at the time), and various weapons. Other than some of the tree, it's nearly all brick-built, in the traditional sense, with very few of the castle wall pieces introduced with the Crusader sets. In terms of play value, it has two secret entrances, with a lookout platform integrated into the tree.
Seriously, this is the perfect set. Everything I built for the next several years was inspired by this set.