Okay, so what do I think of the Slavers modules individually? After all, I salute the effort in getting 'em all out and trying to make 'em a cohesive whole and I think they do a good job of that. But as individual modules? Seeing as how I like to rank my adventure modules separated into their component parts, rather than as supermodules....
Welp, I kind of have to rate them in order...in other words, I feel A1 and A2 are the weakest individually, A3 I like a bit better, and A4 is definitely the crown jewel of the bunch...in fact, the latter really deserves its own blog post (we'll see if that happens).
Now having said THAT, I would like to point out that I have only ever ran A1: Slave Pits of the Undercity. As mentioned earlier, I owned the supermodule at one time, but never had a chance to run it (or even finish reading it!) prior to somehow losing the damn thing. What this means is that my impressions are entirely academic, i.e. theoretical...the true measure of an adventure module is how it plays, not 'how it reads.' So until I have a chance to run A2-A4 (and I should probably run A1 again as well), how they compare to each other is a matter of (academic) debate.
But I can at least give impressions/observations based on a read of the modules with the eyes of an experienced DM.
A1: Slave Pits of the Undecity is the first module of the series, and is written by that master of B/Expert game design, David Cook. It certainly shows a couple of what one might consider Cook's "hallmarks." For one thing, it is set at what (in B/X terms) would be considered "Expert level;" that is, levels 4-7. This is right on par with his Desert Nomad series, the Isle of Dread, or Dwellers of the Forbidden City...in other words, the levels where he has displayed a bit of mastery (in my less than humble opinion). The other thing is the inclusion of the insectile Aspis monster which definitely has a Sword & Sorcery (i.e. "pulp") feel to it that is also present in his better modules.
However, I can't help but feel disappointed in A1, especially in comparison to the other modules of the series. Perhaps it was specifically meant to be a "warm-up" to the other modules; perhaps Cook was not at his best when designing "tournament" modules (I note that he did not write/design any of the "C" - "Competition" modules for TSR). But much of the adventure simply feels like the monsters have been chosen only with an eye to providing the correct "level of challenge" for the characters (the proper number of humanoids, the occasional spellcaster or undead, a not-too-clever trap here or there). Perhaps because of the venue (i.e. tournament) there is little of the leeway or latitude allowed for creativity as present in Cook's other modules. Simply compare the thing to the open-endedness of I1:Dwellers of the Forbidden City or X4 and X5...the whole adventure feels constrained and, I'm afraid, a bit dull.
A2: Secret of the Slavers Stockade, described by one review (per wikipedia) as a "good, workman-like adventure" is the longest of the series, being 40 pages in length and almost totally devoid of interior art. Personally, I find it incredibly interesting that Tom Moldvay was a co-designer in this module...this is the only AD&D module that bears his name as a designer. His other modules are all for B/X or the B/X-derived BECMI (his one module of the latter being a Master level adventure). Seeing his name on it is a bit like seeing Holmes' name on an AD&D module.
I LIKE A2 as a module, but I find it to be derivative...that is, it bears a lot of resemblance to the G1-3 series. Here is a fortress the players must enter. By stealth or by combat they must wipe out the inhabitants. Oh, then they find a scroll that tells them there's a DIFFERENT place to go to. Not much here that hasn't been seen elsewhere.
And as I said in my earlier post I consider published adventure modules to be a key method of informing D&D play. At least, they were in MY youth. You can read the rules set for a game, but without specific examples of dungeon design (Tom Moldvay's Basic set, for example) it can be tricky, putting it all together without a mentor to guide you. TSR's adventure modules worked as mini-mentors for those of us that were "self-teaching" ourselves to play. And while A2 is a nice little (or medium) adventure, it ain't teaching anything new.
Really. For example, it does have nice character: unlike the first module of the A series, A2 bothers to name its slave lords, give them some personality, and tweak them slightly with special abilities (the "blind" fighter that is immune to visual spells, the ogre with his ability to disarm foes in combat). But this isn't much different from King Snurre and Queen with the special auto-kill attacks, or Obmi and his slyness.
What I'm saying is that the best adventure modules of TSR's early years each provided something special to the developing DM: Tomb of Horrors gave us the "monster-less" dungeon, White Plume Mountain gave us riddles and special magic items, Barrier Peaks mixed sci-fi with fantasy, the D series provided the epic and wide-open Underdark, Shrine of Tamoachan mixed in Aztec mythology, Isle of Dread gave us a dinosaur "lost world," etc.. I don't see anything new in A2 that would help inform play, or help a DM "take things up a notch." And so, over-all it feels weaker than the later modules of the series.
Which it appears will have to be a separate post, based on the length of this one....