I bought this and gave it a first read-through.  It is an excellent conversion of one of my favorite classic low level adventures, updated for 5e.  There are some new monster stat blocks and minor magic items, a little town map on a peninsula (which makes it easier to locate the town on almost any coastline), options for expanding some areas, notes on factions, rumors, and ways to tie Portown to Saltmarsh, plus even 4 pre-gen PCs. Check it out.

Finally had the time to read The Ruined Tower of Zenopus: link @zenopusarchives has done an AMAZING job with this 5e update of the Holmes sample dungeon,

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.