Erik Jensen took the time to write out a nice review of the Ruined Tower of Zenopus in a series of tweets (also copied below).
Erik is the writer of the Wampus Country blog, organizer of Tridentcon, and GM on the schedule for Scrum Con this year and has a "Lumberlands" zine forthcoming. I've met Erik at Tridentcon and Charm City Game Day several times; in fact, the first time I played 5E was in a game he ran at CCGD.
It's hard to get reviews for new products, so I want to thank Erik for taking the time for this:
It's a solid dungeon using the classic map, but it's more than that. It's a great campaign starter for 5e with old-school sensibilities and trappings. It has new 5e monsters and items. Zach gives us 1st-level pregens.
Tips for situating the thing as part of 'Ghosts of Saltmarsh' to turn the beginning of that campaign into a sandbox. You want old-school? A nice rumor table. A delineation of the factions in the dungeon. A list of classic AppN stories that probably inspired Holmes' dungeon.
'The Ruined Tower of Zenopus' is, stunningly, only $1.99. If you're a 5e DM, pick it up and put it in your go bag. If you're an old-school DM, pick it up and see what Zach did with this baby, you'll appreciate it. Strongly recommended, looking forward to using it myself.
Get the Ruined Tower of Zenopus here on DMs Guild!