As a 3D platformer, this game is fantastic. Beyond the movement being extremely fluid and responsive it has an aspect that I seek out of 3D platformers, expressing yourself with said movement. You can, in a way, sequence break levels, which I did a lot by abusing the wallkick, to the point that the bounce jump was the very last upgrade I got. It's the perfect combination of letting you go crazy with the sandbox of movement, but also incentivizing you to do so.
However, as a metroidvania, ehh...
The combat just sort of exists and while the lack of a map is a problem the real issue the lack of direction. It never actually feels like any of the areas are connected, so a lot of time I got this feeling of "Oh, I'm here?" At the very least I appreciate the game's direction of "Just go find these 5 thingamagigs and get to the end."
The foundation is more than great, so I'm hoping a sequel comes one day to polish the rough edges.

Abide with Rubicon.
I'll admit that I am somewhat biased with this review, I have played almost every AC game, from 1 to Verdict Day, and am overall a really big AC fan.
With this in mind, how's the game? It's almost everything I wanted.
The gameplay is a blend of 4th gen and 5th gen, focusing on the bigger setpieces and bosses like 4th gen, but being slower, further allowing for more strategies. Add a Sekiro-esc stagger system and you got the best gameplay loop in the series.
Furthermore, it has the best story in the series, every character is entertaining, and I love the little additions new game+ and ++ add.
I also appreciate the level variety, while it is somewhat of a shame that there's few levels where you fight gigantic machines ala For Answer, it is good that even the simplest levels at least have a gimmick or two to spice things up.
My only real complaint about the game is that the OST is disappointing, it feels like Frequency/Kota Hoshino focused too much on atmospheric tracks, and while that fits the mood, I expected a lot more songs with vocals, or at least rock ones. That said, there are some songs which do scratch the itch.
Overall, the game is amazing, feeling like a mix-match of everything good from all AC games in every sense. If you keep your eye out, you'll notice indirect references to the other games, evolutions of their themes and style. I'm really hoping FromSoft looks at the success of this game and keeps the series alive and well in the future.