A comprehensive and well-researched opening repertoire based on a delayed or pseudo Catalan. I would not, however, consider this a "simple" repertoire. Positions can be quite complex, and White's setups and move orders can vary quite a bit based on subtleties of the positions, making some lines hard to remember or implement (for me at least). The opening analysis is very good, and clearly viable at a high rating level. Mostly the analysis is very good, with a lot of variations and possibilities covered with text explanations. I have also felt the plans and continuations into the middlegame are pretty clear. I don't feel like the Catalan is the most challenging approach against everything Black can do, and the book freely admits this while finding lines that are at least safe and give some pressure or pull in the position somewhere. So I may end up incorporating these lines into a larger repertoire. But I definitely think there's some great analysis in here and I recommend it for intermediate players or above who want some more options when playing 1.d4