Well, I think Monte did a pretty good job with this. It's not perfect, but then very few modules ever are...
It does work in the sense that it is what your DM makes of it, here is what I am doing to my group:
(All apologies if I don't use proper names I don't have the modules with me...)
General Premise: The odd looking "spikes" that show up underneath the moathouse, and in the middle of the crater lake, are actually physical manefestations of the "pins" that keep the Big T trapped in his prison. For reasons not explained these pins attract dragons (helping to explain the presence of so many dragons in a greyhawk adventure, something that I needed to do). Dragon eggs are corrupted if hatched in close prosimity to one of the pins, creating: Draconians (ala DragonLance).
Characters start a level 1:
Begin with Sunless Citadel:
Place the citadel on the edge of the Orcish Empire of hte Pomarj, the Suss Forest, and the Wild CoastThe corrupt tree is there because a "Pin" is underneath it, and the evil of the Big T creats the the whole premise of the module (the reason for the collapse, the reason the kobolds (related to dragons) are there etc. THe original mission is to recover some unknown piece of information. Party sees lots of draconic themed items (as per the module, again laying the groundwork for the dragon/spike/Big T connection). They find the scroll with the obscure dwarven text. Turn this into a missive from the dwarves from the crater lake, giving the PC's clue later on that there is a sanctuary in the cave complex (2 of the PC's are dwarves...). Replace the troll priest with a Bozak priest, and perhaps 2 baaz guardians.
In the end they recover information leading them to lost city of the Suloise in the Suss. Character leave at level 3.
Next part: Journey to the city of Xak Tsaroth (i.e. module DL1).
The party will have to be on their toes as they learn that others are searching for the same information (the Black Brotherhood, who will serve as enemey NPC's of both the PC's and the Big T worshipper at the crater).
DL1 was written for 4th or 5th level characters, so the intent here will be to gather information, see more draconians, and perhaps begin to put together the idea that the sunless Citadel and Xak Tsaroth have something in common (why did they both sink....). If they are smart, and ROLE play, they won't get into many fights, and will get out with information leading them to Hommlett, and RttToEE begins.
In the modules I replace many of the hack humanoids (hobgobllins and the like ) at the crater with draconians, if XP is advancing too fast, use the Black brotherhood to take out enemies in front of them....
I think that this has created a GREAT chance of Roleplaying, and while there will be plenty of Hack n Slash, the party will have to be thinkers to survive...
Why'd I write all that? I dunno, but maybe you'll find it interesting...