Two things.
Knack looks like a badass.
Knack sounds like a badass.
I'm in complete shock at how repulsed people seem to be with both aspects of Knack's character. I'd love for people that loathe either to really articulate what it is they hate so much about it, because I certainly can't figure it out.
On his voice, he comes off as a big lumbering badass. His lines, like most of the writing in this game are very campy and playful. To me, I'd relate him to a kid-friendly version of Kratos. Like Knack, nothing that has ever come out of Kratos' mouth has ever moved me emotionally or developed him as a super deep character, but it's a deep, gruff, voice that exists to say badass angry line #14 at the right moment. Knack is on the same level to me. A fighting machine that talks. There are some nice unexpected little moments. I love Knack's little quip when he's prompted to the ice crystals for the first time. He imitates the professor, "the arcane relics blah blah blah.." He's not overflowing with character or anything, but small touches like that elevate him above the unappealing bland mess people seem to dismiss him as.
I never get the feeling it's taking itself more seriously than it is. I equate the overall writing and dialogue to the level of "just go with it" shallow, playful exchanges found in something like Pacific Rim. You won't get deeply developed characters of course, but that's not why you're playing Knack or watching Pacific Rim. There's an old-school after school anime level of innocence and genuine campyness that feels hard to capture these days. You get a sense of light-hearted adventure and pacing that is rare to come by in a world of gaming filled with gritty serious adults fighting wars, watching your dad get killed, decimating nations…
Now on Knack's design, I feel like it is too appealing to a nostalgic, spiky sense of 'coolness' from days past, through a modern lens. It feels a lot like an extension of the recent Pokemon Mega Evolution designs. It's Charizard!! But with flames!! Spikier!!
But I look at this and my childhood thinks: Awesome!! It strikes a cord with my nostalgia of his old design, amplifying the characteristics that made him memorable in the first place. While Knack is a new character, I still get the same feeling.
How is this such a shitty design? How is it so different from the new Charizard designs that people trip over themselves to praise?
This will come off as a lot of crazy talk I'm sure, being in the minority. But I thought I'd at least attempt to explain why I really dig Knack's character in an ocean of hate. I'm fascinated to know why, since maybe I'll be the one walking away with a better understanding/taste. Blegh, this post got long.