Heavily divided on this one, the system driven level design is excellent, the apex of the franchise, everything is polished and works as you would expect, enemies react as it should and you interact with the world appropriately. The problem is that Ubisoft knew this, so the rest of the game is poorly done, being the grindiest as well as having the worst story in the franchise. Besides that, the whole Assasin's Creed identity is lost, as the story ignores the Creed completely in favour of building a gang (?).
It's a shame, especially after Unity returned to the roots of Ezio's Era, with the Assassin's more present and a urban setting so immersive, something Syndicate does extremely well with London and it's mechanics of building an Creed (gang in this case).
I had fun while playing, stealth is super satisfying and the game mechanics integrate well with the missions, but they only scratch the surface of what they build and is depressing seeing the wasted potential.

Interesting how the game tries to play with the concept of power fantasy on its design but fails ultimately.
Knack always starts small/weak and keeps getting bigger/stronger and gaining different powers (incorporating elements) throughout the levels, which makes a compeling idea in how the player has to deal with the adversities with small-knack (bigger focus on the enemies moves and attacks, as you can die easily) and later with bigger-knack (just smash).
This constant variation in the way the player interacts with the world should be interesting enough, but rarely is, as Knack moveset is so limited (one punch and one 'special') no matter his size, that there's no difference in how the game can be played, just dodge, attack and repeat.
Some enemy attacks are more creative and can complement knack's moveset in a way that makes the combat work, but you can count these instances.
In the end, Knack is such a simple game that it's hard to not think this was halfway in development when released.

I was expecting that a console launch game directed by the lead architect on the console itself would use more of it's functionalities, half of the buttons on the controller aren't even used.

This place is a message... and part of a system of messages... pay attention to it!
Sending this message was important to us. We considered ourselves to be a powerful culture.
This place is not a place of honor... no highly esteemed deed is commemorated here... nothing valued is here.
What is here was dangerous and repulsive to us. This message is a warning about danger.
The danger is in a particular location... it increases towards a center... the center of danger is here... of a particular size and shape, and below us.
The danger is still present, in your time, as it was in ours.
The danger is to the body, and it can kill.
The form of the danger is an emanation of energy.
The danger is unleashed only if you substantially disturb this place physically. This place is best shunned and left uninhabited.