The cover art was great... Not to be too harsh, but the rest of it (plot, etc.) did nothing for me, unfortunately.
It seemed too "old school," which is a bit funny coming from me (your dad got me hooked on D&D back in the day, LOL, and I look back fondly on most 1e modules). What I mean is that Gaxmoor seemed to be one big, mindless dungeon crawl with little in the way of rhyme or reason, and I really don't like "epic" modules like that (Ruins of Undermountain being the greatest offender in my mind). Additionally, Gaxmoor seemed much too deadly for starting characters and there were way too many mistakes in the d20 stats as others have said. I don't think the project was hopeless, but it should have gone through several more drafts before going to press, to clear out the rules bugs and clarify how to scale it for beginning characters, if not to flesh out a more catchy plot and NPCs/intrigue.
I was very excited by the cover art, but after flipping through the book, all my enthusiasm went out the window and it went right back on the shelf... As did dad's Canting Crew. At least Gaxmoor wasn't overpriced and artificially inflated in its page count like Canting Crew was.
Troll Lords seem like nice guys but I haven't bought any of their products yet due to one issue or another spoiling it for me. Still, they are improving and listening, so I hold out some hope that I'll finally be able to buy something from them within the next year or two.
**fingers crossed**
Hope this helps out with your next project and good luck!