Hi, Mouseferatu. Thanks for your reply. I hate to write a bad review of a product, because I know that we all just love games here. Since you invited my response, I'll clear up any questions you have, and address some of your comments.
A friend suggested that I preface this by listing my two criteria for judging adventures: 1) good ideas and 2) save me time. I can write stories and stat out my own enemies. All I'm looking for from adventures is an idea that hasn't occurred to me, or stuff that I can use in my game (towns, NPCs, encounters, etc). Any extra work that I have to put into the product to make it work (above and beyond understandable conversion to an existing campaign) is a negative. So, when I have to correct anything, it bugs me. When I have to correct a lot, I'm basically doing what I could have done myself, except that I paid to do it.
I've quoted your responses and trimmed out my statements that you were replying to in order to save space. I'm replying to your comments.
"Okay, this one puzzles me. Why is 4th level to 6th level a big deal? It's a fairly lengthy module; is a two-level gain really so unusual?"
I agree, it's not. That's not what I was saying. Me having to figure that out is frustrating, when you (the author) knew it and didn't tell me. Other adventures I buy list this information, why not this one? Even a table of ELs would have been enough to see this.
"What [city] stats were you missing? All the basics--population, population breakdown, economics--are given for both major cities. What else were you looking for?"
In every product I've purchased, the first part of any city's stats is the City Type (village, town, small city, etc). It gives the most immediate picture of the settlement. They weren't included.
"Still, [ELs are] an easy mistake to correct. Just add 1 to the CR of all the leveled drow NPCs."
I understand that it's easy to correct, but at the same time, I bought this so that I wouldn't have to correct these kinds of things. I'd feel differently if there were an errata on the Monkey God website.
Even so, it's more than just bumping up the EL/CR and the problem goes away. It bugs me that I have to second guess what you wrote. Now I think that I have to scrutinize the rest of the encounters, in case another one is off and therefore going to be more deadly to the PCs. Does it matter when we're talking the difference between an EL(Party Level) and an EL(Party Level + 1)? Not really. Does it matter when it's EL(Party Level +2) or EL(Party Level +3)? Yes, very much.
"I know a lot of people--myself included--who prefer having monster stats reprinted in the module, to avoid having to go back and forth to the Monster Manual."
It's a taste thing, I know, so I can't disagree with you. But when it's my money, I want to see stuff I like, and that ain't it.

If I had noticed that, I might not have purchased it.
""This adventure is incredibly poorly thought out in terms of rewards.""
"Hmm. One or two items--such as the Bracers +6--are indeed higher than "book value" for a group of this level. I did that deliberately, since many of the encounters don't provide treasure at all. That said, however, all the other items you specifically mentioned are entirely in line with the EL of the encounter in which they appear. I believe that the vast majority of the treasure rewards are commesurate with the encounter level of the encounter in which they are gained. If that's not the case, I ask you to point out to me where I goofed, so I might watch for similar mistakes elsewhere. Please feel free to respond by e-mail, if you prefer."
Here's two examples:
In an EL5 encounter, a third level drow cleric has a +1 Shocking Burst Light Mace and a +2 Buckler. Total value: 22000gp.
In an EL6 encounter, a fifth level drow cleric has a Minor Cloak of Displacement, which goes for 25000gp.
Grand total "book wealth" for a 6th level PC: 13000gp. It's a good rule of thumb that no PC should have a single item of value close to or more than their DMG equipment guideline. Your adventure has seven (Staff of Passage, Minor Cloak of Displacement, +1 Shocking Burst Light Mace, Ring of Chameleon Power, Bracers +6, Ring of Evasion, Wand of Dispel Magic). All for the PCs.
All the stuff that secretly turns a 6th level character into an 8th or 9th level character. This breaks the game, and when I see something like this in a module, I can't use it.
"Again, I'm not trying to change your opinion of the module. You didn't like it, and that's fine. But I felt the need to, at the least, explain where/why/how some of these decisions and mistakes were made. Hope you find my future efforts more to your liking. "
I appreciate your thoughts. I hope that I like your future work more, too.