In terms of basic game design aspects, I am of a mind that less is more, and TB2, like its parent BW/MG systems, is definitely more of a 'more is more' kind of design philosophy. Also the books are horribly badly organized
I will also echo that the books are awful. I stopped reading them because I thought I had read enough of the Scholar’s Guide (up through town phase), but it seems like that’s not enough. While the Lore Master’s Manual is purportedly optional, it seems like one is best off to read all the things.
I find the rules overly complicated, poorly written, and poorly organized. It has many distinct yet interlocking subsystems: abilities & skills (with several special ones that have additional rules), instincts, traits/checks, wises, persona points, fate points (because why have just one currency?), conditions, conflicts, arcana, invocations, and more. Every rule seems to have exceptions. No given thing is described completely in any one place, except perhaps spells & invocations: I was routinely suprised to learn new things about something I thought had been covered as I read through the two base books
Spells and invocations are also covered in the conflicts chapter of the SG, though I think it might be overlap rather than new information.
It's interesting to see such unanimity with, or even stronger opinions than, what I said in the OP:
Although the two core books are, in both title and the way they address the reader, meant to emulate a PHB and DMG, I don't think they fully succeed in that respect. There is stuff in the Scholar's Guide that players absolutely need to know, including the core action resolution rules; and personally I would have found it easier with a different approach to the presentation of the material, with less overlap between the two core books and less need (as a reader) to read across multiple books including the Lore Master's Manual to get the full picture of a particular subsystem.
On the "more is more" thing, I remember reading a rpg.net review of a Luke Crane game - Mouse Guard, maybe? - that objected to the two currencies (Fate and Persona). Of course Burning Wheel has Deeds points as well!
The rules are difficult to learn, but once you have a grasp of them, they do work. But they are always front and center, standing in between me and the unfolding drama/action, as we go from the description of the situation, to determining which currencies we have in what amounts and how to combine them to deal mechanically with the situation.
This also seems consistent with the OP:
At a high level of description, Torchbearer can be compared Dungeon World: a modern system dedicated to capturing the feel of classic D&D. At a more detailed level I think there are significant differences; I'll get back to these below.
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Here's my second serious thought: Play looks incredibly demanding and unforgiving. This is probably the biggest difference, at least on reading, from Dungeon World. There is not the soft-move/hard-move structure of DW; as in Burning Wheel, many checks will probably be failed (due to high obstacles relative to the abilities and augments the players can muster), but unlike BW there is a systematic process for inflicting consequences in the form of debilitating conditions
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The death spiral, with multiple layers and moving parts in terms of both PC build elements, the basic structure of play, and the passage of both at-the-table and in-game time, seems as severe as anything I've seen in a RPG.
On reading, it's very hard to tell how the flavour and the play will intersect
But I don't think my OP quite called out the place of the mechanics in the scheme of play (in Baker's terminology, how much time one spends dealing with boxes rather than clouds).
Finally, this reminded me of the experience of my own play, limited as that is:
Even though I can point to the items on my character sheet that show Jakob has gotten some nice gear, it feels like he’s no better or possibly worse off than before we started playing.
The PCs in my game, leaving town after their first town phase, are no longer fresh, are still Resources zero (having spent all their loot), and have fewer supplies. In exchange, they have some advancement checkboxes ticked (though no one has actually advanced a skill or ability yet) and they have some Fate and Persona. (But not enough Persona, after two sessions, to earn second level, even if they were to spend it all.)
Also, one has added to his Enemy list, while another has learned that her Friend has been captured by her Enemy.