Nice and practical repertoire book but neither overwhelming nor theory-changing.
From the preface: „My goal was to create a repertoire that allows us to reach the middlegame with a solid foundation while not depending too much on exact theory. Instead, the focus is on strategic plans and positional understanding.“
That‘s why Lemos often goes for side-variations within the main lines. He doesn‘t seem to care for other authors and there‘s no bibliography. He only mentions Mega 2018 and CB Online Database.
Indeed, against the triangle he recommends 4e4 dxe4 5Nxe4 Bb4+ 6Bd2 (Carlsen-Anand 2013) but concedes some black possibilities to gain equal/unclear play.
In the QGA with 3e4 e5 4Nf3 exd4 5Bxc4 Nc6 60-0 Be6 he has the interesting 7Nbd2!? which is not mentioned by Rizzitano or Semkov. But here Lemos neglects 7...Qf6!? as played in some corr games and also in Grischuk-Radjabov (Gashimov Memorial 2019, 3 months before Lemos‘ preface).
In the Tarrasch with 9Bg5 c4 10Ne5 Be6 11Nxc6 bxc6 12b3 Lemos only examines the older 12..Qa5 but not 12..h6 (Aagaard/Ntirlis).
I could go on and on with such little inaccuracies.
The general presentation with plans and motifs to play for seems very good, especialy the chapters on QGE and Slav Exchange on the whole are fine, not only because of the well chosen games! But the devil is in the detail, and despite some interesting lines and a little bit of original analysis stronger players will dislike several parts of the book.
It‘s certainly a good book (4 / 5 stars ?!) for 1600-1900 players who want to start with a 1d4 mainline repertoire with much but not too much theory.
It‘s probably no must-by (2,5-3,5 / 5 stars?!) for stronger players.