I just finished this adventure, and what can I say...I have mixed feelings.
tl;dr: I would treat this adventure as more of a campaign setting. Take the elements here that sound cool and use them, but I would not recommend actually playing this as written. I didn't have fun with this one.
For context, I didn't run this with the G or D series modules. My game ended with a different reason for the players to go into the demonweb. I also never played AD&D, though I love to go back to classic modules for the sake of pulling some of that old school design into my 5e games.
First, the good (beware ye of some spoilers):
There's some really cool stuff in here. I appreciate having an adventure set in the demonweb, with a final fight against Lolth. The way that spell effects are changed by the Abyss is a fantastic touch. I also like the way that the demonweb intersects with itself in ways that don't make spacial sense. These two factors really push forward the context that you're in the Abyss; the old rules don't apply. Lolth's ship at the end is pretty neat, and I like the layout of the spider ship.
But unfortunately there's a lot here I don't like:
Exploration is non-existant. The demonweb is one super-huge totally uninteresting 20 foot wide corridor. Each level looks the same as the last. The most interesting thing is that players (and enemy monsters) can jump off of some parts of the web and land on others where the paths intersect. This is really cool in theory, but in practive the players have no idea where they ended up. Mapping something like that is impossible, and it was probably done that way on purpose to drive the players (not the characters) insane and get them lost. Rooms in the demonweb (what few there are) are stretched hundreds of feet away from each other, meaning that the majority of "adventuring" in the demonweb is going down a corridor, rolling a random encounter every few hundred feet, fighting that encounter, ocassionally coming to a door which you hope is the way up, but it also might just be a room of 30 ogres and they surprise you and you have to fight them. That isn't really "fun" - it's just monotonous. The only cool location the players should visit is the ship at the end. Admittedly, there are seeds of other worlds that Lolth are invading, which is neat! Finally a change of pace. Except they are totally unnecessary to complete the adventure. In fact, the key to these worlds encourages you to railroad the players away and say ”It doesn‘t look like Lolth lives here” if the players get too atttached to the world, or if you can't figure out a way to weave them into the story. So why even have these worlds? Because without them, clerics can't get back any spells above second level. These worlds are on the prime material plane and exist purely for clerics to pray for spells. What a missed opportunity.
Social encounters are vanishingly rare. There are a few places where the characters can meet friendly faces that are willing to talk to them. But none of the random encounters are like that. Most intelligent creatures you meet will attack you on sight because Lolth doesn't approve of interlopers. There's such a missed opportunity here for more social encounters: Driders looking for redemption, demons trying to tempt you, parties of devil spies or agents of rival demon lords coming into conflict with you. The closest you get to that kind of social interaction is the prime material worlds on the fourth level of the web. But I was so drained at that point, I just wanted it all to be over. Those encounters should be peppered throughout the web and not limited to the final rooms of the adventure.
And as for combat; most encounters are honestly really lame. This is the demonweb! Lolth's home base! And most of what you fight is ogres, drow, and giant bugs. Where are the demons?! Why are all of the random encounters fights with giant bugs? And I found most of the encounters are totally meaningingless battles at that. They're mostly fights for the sake of fights; there to pad out the empty demonweb while your players slowly get lost, frustrated, and bored.
Overall, I appreciate this module for the good ideas that are there. And if your group is full of butt-kickers who just want to roll dice and kill things, this adventure might work for you. But I wish there was more substance here aside from killing bugs and ogres. If you're a better DM than me, I bet you can make this adventure shine. But it needs a skilled DM and a lot of polish to bring it to greatness. And I felt the adventure didn't make that easy. So, I can't recommend it