Quasqueton said:
<debates whether this too will be taken as a veiled insult. hopes it want be.>
No, not at all. You've clarified your position, and I apologise for jumping the gun, so to speak. It's all copacetic.
As to particulars...
I've used this module twice, both times stripping out the quest for the Crook of Rao and the meeting with Tenser. Initially, the Player Characters found a map along with a bit of a journal that gave mad ravings of "Oonga" a brutish god on some far distant tropical island (lifted completely and without apologly from the premise in the original
King Kong--one of my favourite movies of all time). Using the map as a guide, the Players set out to find and explore the island (they were enticed by the journal's mention of the brute-god's fabulous treasure).
This party was lower in level than the recommended 15-18th given in the module text (they were to 10-12th) but they were many in number, being 7 PCs and 5 henchmen, with attendant hirelings and the sort. (All told, I think 50 in all set out on the expedition, including the ship's crew.)
The battle with the native tribe on the penninsula was nothing short of a blood-bath. The party prevailed in due course, but almost all of their hirelings and men-at-arms were slain. (No PCs or henchmen lost.) Unfortunately, they killed the Big Witch Doctor and never divined the secrets of the stone pillar. Bringing ashore the ship's crew and the few remaining hirelings left aboard, the party established a base in the Kawibusa's village and from there proceeded to explore the island.
Over the course of two month's game time they made numerous forays inland, battling dinosaurs and happening on some of the weird sites and locales established there by "forgotten" powers. They made friends with one of the native tribes, but violated some taboos of the other, which led to animosity and skirmishes, which led to the tribe eventually attacking the party at their base camp en masse and forcing a retreat from the island. Prior to all of this they had one brief encounter with Oonga, which they fled after he handed them their butts on a tray, as it were. (Two PCs were killed--but brought back--and one henchman was killed and vanished into the jungle clutched in Oonga's mighty paw.) Two of the other gigantic apes native to the island were killed, as well as a slew of dinos and other terrible creatures.) After their retreat the party returned to more familiar locales, and eventually went into semi-retirement (current status, though some Players have intimated they'd like to revist the place).
The second time I ran this module I used it much as EGG might have--a pocket dimension off a main dungeon (which also included a portal to Yuggoth, and one to our modern-day hometown). The party that entered was similar in level to the one described above, and about the same size, but without the hireling contingent. They took a much more commando-approach to the whole affair, made heavily use of invisibilty and illusions to get by the Kawibusas and tramped around for awhile before making friendly with plateau-dwelling natives (after they realised they were stuck here). After proving their worth by leading a few skirmishes against the Kawibusas, the Shaman gave them some indication that the cave of Mighty Oonga might hold the answer to getting them "home". The party obtained the second part of the ritual from the cave-dwelling natives after helping them recover a totem stolen by a band of Kawibusas, but they soon fell afoul of a large force of Kawibusas, and most of them were slain. The three remaining PCs decided to forgo the affair ("for now", at the time) and decided to stay with the plateau-dwellers and become part of that tribe. (We started a new party and gaming went on. We never got back to those three, but as one was a magic-user, I'm thinking the plateau-dwellers are destined for great things in the future...

. )
Anyway, great, great fun, but definately needs to be treated as a setting-module rather than an event one (as with the D-series modules). Players and DMs seeking to hack their way from one end of it to the other in a linear quest fashion aren't going to like it, I should think, but with the right spirit and a more long-term approach, I think it would add a great deal to any campaign. Issues vis design approach and the handling of certain spells are best regarded as matters of personal taste--it won't be everyone's cup of tea, certainly, but in the context of a truly isolated "lost world", neither I nor my Players had any problem with it. (Should note that Zagyg isn't a part of my campaign, but the weird sites spotted about the isle and the magic interference were held to be the result of heretofore unknown powers long forgotten by the natives of the place and the rest of the world at large, as well.)