A definition from Grognardia:
Silver Age (1984-1989): The Silver Age is a transitional age that marries a sophisticated (some might say "decadent") interpretation of Gygaxian naturalism with a growing concern for "dramatic" coherence. The Silver Age is one of "fantastic realism" and the construction of believable worlds and stories is its great concern. It's also the age where the Great Wyrm begins to eat its own tail, being influenced not just by epic fantasy generally but more specifically by second or third order epic fantasies that were themselves influenced by D&D. The Silver Age is when the mass marketing of the game begun in the late Golden Age reaches its fullest flower.
Unfortunately for me, the WSG is just too unorganised and not inspirational enough, to work as anything more than a guide for the sake of a guide. Rules for rules sake. It is a Silver Age publication, for these reasons, and fails for the same reason.
I have been asking myself if I would have felt any different in 1986. I think the answer is no - but that is a difficult one.
Now unorganised may feel harsh when the contents are very clearly set out, but the rules are spread throughout the entire guide. So land-based mounts are: characteristics 90-91, combat 16,86, fatigue 88, lack of food 52, movement 32-33, reactions 92.
This might sound like the Dungeon Master's Guide, but it had an inspirational charm, that surpassed it's design flaws.
I'm not sure what publishing pressure Kim was under, but the WSG comes up short, and much shorter than the Dungeoneer's Survival Guide. The DSG made me want to take my players spelunking.
Could I have done better?
I am sure I could not. For proof, see my dormant Old School Adventure Guide - yep empty.
What would I have liked to have seen then and what would I like to see now.
I think if the book had been broken into terrains, it would have been stronger, far more useful and have become inspirational.
e.g. Arctic - with rules for cold, a new equipment list (sleds, warm clothes, eye protection, new spells, and monster section (including huskies, polar bears etc).
And so on for desert, forest, plains, mountains
You see as DM, the setting can often fire the imagination. Rules don't do it alone, and I like rules. Wilderness is just too broad a terrain type!
I might want to take my players to Hoth - if so I want rules that deal with this easily accessible, not rules on cold spread throughout the entire guide. After reading these imagined arctic rules, perhaps I may have been inspired to take take my players to Hoth, even if it had never occurred to me before.
Or Tatooine, or up the mountains. Or in the open plains, where horse lords rule.
I also think these guides would have been more effective if sold with a DM screen - all relevant tables must be on the DM screen. How much can one remember otherwise?