The criteria I'm looking for are:
(A) encounters that play up various party roles (martial, skill, magic, etc.)
(B) whether the adventure sites have a reasonable ecology (what, no bathrooms?)
(C) the narrative flow of the overall adventure.
Nice use of wintry weather, it introduces a lot of terrain and combat obstacles.
There are a few sentence fragments in this adventure, such as "A trait that’s liable to get someone hurt."
The decision to present the encounter areas out of numerical order (i.e., first Area 5, then Area 4, 3, 2, 1, 6, and so on) makes it hard for a GM to look up information in the middle of the adventure. I understand you presented them in the order the PCs would probably encounter them, but adventures usually present area descriptions in numerical or alphabetical order, and for a reason: that's how people are used to looking up most information.
Including a siege/waves of enemies part in this adventure is ambitious and makes the adventure much like a little mini-wargame. The complexity of it might be difficult for a GM to run unless it's read very carefully, but I think it would be a fun encounter. Not only does it put the PCs on the defense, it forces the PCs to ration use of their daily abilities instead of unloading everything as soon as possible.
(A) Skill characters can pick locks, climb, repair ballistas, and so on. Martial characters have many things to fight. Spellcasters will have many opportunities for AOE effects in the waves portion of the siege.
(B) There are a lot of encounters outside in this area—the dryad/gargoyle encounter is less than 200 feet from the spider lair, all of which is near the tower. There's no information about whether the doppelgangers and mind flayer are allied with these creatures, are controlling them, ignore them, and so on... it seems odd to me that the area around the "isolated" tower has so many unassociated dangers in such a small area.
(C) The flow of the adventure is linear (PCs are driven toward the tower, navigate the dangers of the tower, then deal with the siege) and easy to follow. Even where the PCs have significant choices to make (such as negotiating with the wraith or choosing to defend or flee the tower during the siege), the overall flow of the adventure is unchanged (in other words, unless something really weird happens, the siege isn't going to happen until the PCs have dealt with the mind flayer).
Eclipse Phase Character Generator
SKT Runes for Chapter 4
Mystic Power Cards Template for Magic Set Editor
Warhammer 1st Updated
ForgedAnvil D&D 5E Character Generator
MPMB's D&D 5e Character Tools
D&D 5e Character Sheet - by WastingX
Editable Pathfinder Character Sheet
DnD 5ed Auto-calculating Fillable Character Sheet based on Dragon's Lair Design
D&D 5th Edition DM SCreen
5e Character Sheet - Expanded