Lacking in both depth and quality. And by quality, I don’t just mean the content. I’m also talking about the physical quality of the books, which have been plagued with printing problems that previous editions didn’t seem to suffer from (cheap bindings that fall apart, poor printing controls that result in blurry headings, low quality paper and ink that easily smudges, and so on).
In terms of content, I regard the SCAG and Volo’s as the edition’s best supplements, and neither of those is without its problems (the SCAG could/should have had more crunch in it, including more FR-specific stuff, more spells, and maybe even some magic items; Volo's was fine except for the PC race options, most of which needed more playtesting -- as an alpha playtester, I was disappointed to see that WotC felt the draft versions were good enough to publish virtually unchanged; it's like they just couldn't be bothered to try and balance them and decided to make us DMs do all the hard work*).
XGE was a big disappointment for me as the content is not just a random grab bag thematically but also in terms of quality. The subclass options are very hit-or-miss. So are things like the expanded rules for tools and the revised downtime activities. There’s so much in that book that clearly could have done with more refinement than it got. But again, WotC deemed the content good enough to publish, knowing that we long-suffering DMs would iron out the kinks for them.
I think my main issue with MToF is the choice of content: what they included vs what they didn't include comes across as somewhat nonsensical and seemingly random to me. For instance, there are PC stats for sea elves but no fluff to go with them. And the chapter on gnomes and halflings, while nice, really doesn’t belong in this book, even as a so-called "constrast" to all the other chapters about long-running feuds and the like. And did we really need the deep gnome a third time?! I think “Tome of Foes” was a poor choice for this book’s title, given its content.
And so on and so forth.
Now I spend my homebrew energies on making adventures, monsters, and Immortal rules.
