IGN enjoyed the lead character and its cool concept of growing larger the more he fights. However, they took a few points of the game for its repetitive nature and poor plot execution:
Playing Knack is like watching a dull movie on a plane – it's tolerable if all you want is a way to pass the time, but it's not something you'd seek out for its own sake. I finished in about 11 hours and, challenges, co-op, and secrets aside, there's just not much here worth recommending. Sure, some individual elements show potential, particularly when the scale of the encounters changes as Knack grows, but it never moves beyond playing it safe with the concepts or the characters.
GameSpot gave the game a low score and lamented the fact that Knack's basic gameplay, unmemorable in-game fights and lack of diversity hurt the final product:
Knack's downfall is that it focuses entirely on combat, but doesn't offer enough variety or depth within its system to compel you onward. Any early thoughts you may have that there must be more to the punch-punch-repeat action than meets the eye are banished once you plow through hours of the same basic sequences. And even Knack's few attempts at diversity are merely competent. The occasional platforming scenario lacks the joy of movement so necessary for jumping to be engaging, and the platform placement doesn't require any cleverness to surpass. There's not one element of Knack to rally around, to excite you. And without that special something, Knack crumbles just like its piecemeal protagonist.
GamesRadar felt the game was an entirely mediocre experience. They were quite fine with the game's nostalgic play-style and beautiful graphics. They were displeased with the game's design flaws that make the game not worth remembering or returning to:
There are certain times, when the camera is pulled in tight, that Knack looks like the next-gen showpiece you want it to be. In-engine cutscenes show off the detailed world and fantastic lighting, with wonderful shadows and imaginative characters. And there are moments where the gameplay lives up to expectations, feeling like a modern game with flashes of old-school nostalgia. Problem is, those times are interspersed between design flaws that feel two generations old, making for an uneven, unmemorable experience.
Polygon wasn't too high on Knack, either. They felt the game's single-player campaign was nothing special, plus the payoff moments weren't much of a payoff in the first place:
Knack has too little going on over its 12 hour length. The core concepts are strong - it's fun to watch Knack grow bigger and smash things. The incredible imagination promised by the dawn of new hardware is on display in Knack. But the moments of payoff come too infrequently to make plodding through another three dozen frustrating enemies any less tedious.
Game Informer enjoyed the game's return to the heyday of high-quality platforming. They also felt the game's graphics were a big part of this title's appeal:
Though it's a launch game for a next-gen system, Knack is almost nostalgic; it's the kind of game they don't make that often anymore. As such, it's not the most innovative or the most visually dazzling game. This won't be the one you put in to show off your new console to your friends. However, when you're done with the prettied-up versions of the big franchises, you'll find yourself wanting to return to Knack. It's got charm and heart, and offers a whole lot of good gameplay. Ultimately, that's still what's important - no matter which generation we're in.