Read the third adventure,
The Will of Orcus, which is just a very, very solid dungeon crawl for a 4th level party.
The Good
This adventure gets the party quickly to the front door of the dungeon with minimal fuss and preamble, which is sometimes exactly what you want.
Unlike
@pukunui, I had little trouble with the idea that the cult would be fooled by a silver dragon impersonating their god. The cult really only has 4 sentient members, 2 of whom are wavering. Cults by their nature rely on their followers to accept absurdities as facts, and attract people who can be preyed upon in this way. I find it plausible that someone who managed to con their way into the top position in a cult's hierarchy would, at least for a period, be able to get the members to do bizarre things. This hasn't been going on very long by the time the adventure starts - a week, maybe.
Apart from that twist, it's a meat-and-potatoes D&D dungeon with a lot of undead, good combat encounters, interesting layout, some quite good roleplaying encounters, and okay exploration elements. Again, plenty of magic items but here there's more of a chance that players aren't finding all of them.
Another very good full-color map with 5' squares. With one exception (see Complaints) this map is very well laid-out and allows a lot of pathing freedom for the party. The art for this one is more in line with 5E's traditional style, with a suitably dark palette given the subject matter, with figures positioned dramatically and some nice use of perspective.
Complaints
One does have to swallow the coincidence that the dungeon was abandoned for 20 years and then, almost simultaneously (days apart), a silver dragon and cult of Orcus both show up independently to claim it. It would have been nice if there was some inciting factor that attracted both groups to arrive at this particular time - perhaps the approach of an impending astrological date of significance to Orcus that the cult wanted to capitalize on, and the dragon wanted to ensure that the site wasn't reactivated.
There are two ways that the players can find out that a silver dragon has been impersonating Orcus - one is by encountering the dragon disguised in the temple's inner shrine, speaking commandments and testing them in an amusing way from inside a huge Orcus statue, then revealing himself once they've gained his trust. The second is if the adventurers get into a fight in a nearby room and the dragon just comes running in to help, then has to explain the entire central plot anti-climactically to the adventurers who will have pretty much missed noticing it, at which point the adventure is pretty much over except for perhaps a little mopping up. Scenario 2 is far less interesting, but because of the map layout, is the most likely scenario to happen. This can be avoided just by erasing from the map the double doors which connect area T5 to T12, and closing the doors connecting T12 to T13.
The puzzle and trap elements are just okay. Not bad, but nothing to write home about.
Verdict
Solid B+ or A-. The flaws I picked out above are very easy to address, and apart from those I think it's just a rock-solid 1-2 session dungeon crawl, the twist works, and almost any group will enjoy it.
Having read 3 of the 10 adventures, so far I am very impressed and encouraged by this book. I think many of these adventures were developed prior to or during the development of the 2024 rules, and it does seem to me so far that with the substitution of one or two creatures that only exist in the 2024 Monster Manual, you could run at least these first three under 2014 rules with no problems at all.