One of the greatest indies on the platform. Stop reading and play it.

Pros:
1) Puzzles! They're great. Love the core mechanic and the pacing of new tools.
2) Extremely useful map that is honest about when you're done/when there's something else to do.
3) Writing. "But there's barely any dialogue in the game!" Exactly. More time for puzzles. Your tesseract buddy is also always there to help with small mechanics, so no wasted chunk of tutorial time.
4) Aesthetics. The entire package is great, and you can tell a lot of care went into polishing the graphics and audio. There were a few puzzles that were charmingly synced to the background music, for example. The various environments all look fantastic.

Cons:
None of these are game-breaking but I wanted to air grievances just a little.
1) Repeated puzzles, especially near the end of the game.
2) Movement feels slow, especially during platforming. I would not recommend playing this after Hollow Knight or Animal Well, for example, because you'll feel sluggish.
3) Backtracking when you start a new game mode on the same file. A mild exception to my praise about writing.

Without saying a single word FEZ takes you through a journey from not knowing how the world around you works, to decyphering an alien language through the use of equations in an incredibly intuitive and natural way. Other than maybe Outer Wilds, this is the "Metroidbrania" design at its peak. Out of the 64 puzzles in the game (even tough not all of them feel unique, there are a few repeats) only 1 stuck out to me as kinda odd. It was kind of janky to experiment with and the solution isn't even clear unless you know a specific piece of geometry trivia, or maybe I'm just salty because it's the ONLY ONE I had to look up help for :,).
Overall though, if you're looking for a brain buster, you're bound to have a fun time with FEZ.