I've spent a long time talking about some of the things that are wrong with 5TD's subsystems (most recently magic). I wanted to say "all the things wrong with 5TD" but sadly that's not true.
Most of the issues I've talked about so far have been because 5TD went overboard on making life suck for player characters. But eventually it dawned on me that they missed a central part of the OSR play experience while they were focusing on some of the peripheral mechanical elements.
It's right there in their list of OSR design principles: "Travel and Resources". When I first read that it struck me as not quite wrong, but not quite right either. Travel is a thing that happens in OSR games, yeah, and so is resource management. But that's not the whole story; those are just fragments of a bigger principle.
I'm not sure I've quite nailed it down either in terms that a reader from a 5e rather than an OSR background would get. The closest thing I have is "player-driven exploration". Some might say "agency" and that would be more precise but less clear unless you already know what they're talking about.
OSR play is typically site-based rather than plot-based. You have an unexplored adventure site, like a megadungeon or a 1200 square miles of wilderness mapped on a hex grid. It's usually big - way too big to be cleared in a couple sessions, maybe too big to be cleared ever. Players might have some objectives in that area, but generally not much of a fire under their ass; no saving the world, probably no deadline. They choose where they go, how they get there, and how to interact with the locals on arrival. They have to explore the area to locate their objectives, get strong enough to take them, and then get them home safely. All of this happens over the course of many sessions within the same site. Players gradually build up knowledge of the area, which allows them to better plan their next adventure.
So yes, you have to travel. And yes, you have to manage resources. But there's continuity and discovery and non-mechanical progress within a site. Travel is something you get better at as you discover better routes, and it's very much part of gameplay, not handwaved at all. Resource management is something that you get better at within a specific site as you discover places to recover resources, or shorter and less dangerous routes that get you to your objectives with more resources to spare (Dark Souls does this well). Players are faced with lots of strategic choices, and they benefit from paying attention over the course of a campaign and making good plans based on what they've learned. It is up to them to choose what risks to take, where to explore next, when and where and who to fight, when to flee combat, when to call off the expedition as a whole. Their fates are very much in their own hands.
5TD's DMing advice touches on considerations of choice and exploration on page 43. I disagree with some things here - "Making sure choices are meaningful demands complex and dramatic situations" is, I think, simply wrong. A meaningful choice is one which has foreseeable, significant consequences, and where no option is unambiguously superior (so not a null choice). Drama has nothing to do with it. I also think that "[5TD] does insist that the game have a sense of exploration, discovery, and wonder" sells exploration far short. Only a sense of exploration? What I'm after is to pose players with problems and choices analogous to those their characters would experience during exploration; in effect to create the experience of exploring. I think this is a good heuristic for mass combat and domain rules too - are you making players make the same sorts of choices that trouble generals and kings?
But by and large the principles on page 43 have the right idea. The trouble is that the rest of the book doesn't back any of this up concretely. Hence, a principle recognized, but unemphasized.
There's no advice on building adventure sites for long-term use, none of the standard tricks like jayquaying (though this might emerge sometimes from their generator system) or restocking or empty rooms or danger gradients / dungeon level or random encounter tables as a means of characterizing a place. One might reply that most OSR systems don't explain these things either, and that's true - but most OSR systems come with paint-by-numbers rules for building dungeons that tend to achieve these properties without the DM having to understand the theory. The example dungeon for 5TD's rubik's cube generation method is nine rooms. This would be small indeed by OSR standards. It's only one page so one can only expect so much, but it could certainly give newer DMs the wrong idea. My typical dungeons are closer to 100 rooms, and many OSR dungeons are much larger. The example adventure they give in the DMing advice has the players choosing which of three points of interest at a site to investigate, not crawling the site with strict time-tracking during exploration, and while it does strongly suggest having multiple factions in each adventure, it also suggests forcing players to choose between them. That's not how player-driven games work. If a faction has something that they want, players will naturally align with them out of self-interest. You don't need to impose a "time-sensitive choice that compels them [players] to go down one (potentially) irreversible path," especially not every session like 5TD's DMing section suggests.
I think we also see this lack of interest in choice and exploration-type gameplay in the mechanics. The mechanics for exploration and traversal of dungeon environments are lighter than even B/X's. Trapfinding requires DMs to provide environmental clues about the presence of a trap and suggests forbidding players from rolling dice unless they propose specific things that they're trying, which is well and good. And there're rules for different amounts of lighting, though their effects are mostly on combat. But there's not a damn thing about secret doors or stuck doors or listening or smashing locked chests or spiking doors shut or non-combat movement through the dungeon. There's certainly no mention of the players drawing their own map of the dungeon or the wilderness as they explore it! While 5TD has overland movement rates modified by terrain and weather, the only other wilderness systems are foraging for Supply, ration consumption, and the same random trouble table as in the dungeon - not even rules for getting lost. Timekeeping rules are present, but the unit is the hour (both in wilderness and dungeon), and "As a rule of thumb, a GM can count every 3-4 scenes, rooms, or encounters as one hour." This is very loose. 5TD's equivalent to the random encounter roll is also very loose - rather than being a table of monsters, it has some vague suggestions about escalating danger level at different rates. Looseness in timekeeping makes it hard for players to make good plans and take informed risks, and it certainly doesn't put them on the horns of dilemma in deciding between spending a turn listening at a door or saving that turn and just going for it. I could see it sort of working for a node-based dungeon where moving between nodes takes an hour, and dealing with a node takes about an hour. But that is hardly representative of the way dungeons are typically run.
In effect, non-combat dungeoneering gameplay is largely ad hoc in 5TD, rather than being a systematic game-loop as in OSR games of D&D lineage.
Involved fix: graft B/X's exploration rules, noncombat movement, and timekeeping onto 5TD. This also addresses issues with encumbrance and resilience penalty gradients.
Involved fix: provide better dungeon-building advice.
Involved fix: provide better DMing advice 
In closing: I have said all that I aim to say about Five Torches Deep. I think they chose bad design goals and then implemented them heavy-handedly. I think they also missed at least one of the defining features of the OSR playstyle in implementation. I think a much better OSR/5e hybrid is very doable. I hope someone will make it. For my part, I think I am not the one to make it, as my familiarity with 5e is too limited. If someone reading this does take up that cross, I would be happy to review your draft or otherwise consult.
Thank you for reading all of this. This review is right around 10000 words, or 20 pages in a word processor under default settings. It's been about a three-week project. The text-heaviest of 5TD's pages are about 700 words, and there are 36 non-art pages, so this review was conservatively 40% as much text as the product itself, which is a new one on me.
... maybe I'll just take a peek at Homesteads. I did already pay for it...