This may be a personal nitpick of mine, but some of the drawings, and movements in particular, seem a bit off. I would expect the movements to be stiff, that's fine, it's the nature of the strip, but many of the pauses in the animation, especially during the pouncing seen, kind of break it up a bit.
As for the drawings, though the background is WONDERFULLY animated, many of the lines seem somewhat thick and solid at moments, which in any other case would be helpful, but here, it's a tad distracting. The original material, though it also had SOME thick and solid lines (That's the nature of writing...), it was still very clearly done in pen/pencil by a casual artist or cartoonist, as many of the lines were thin, and the style remained open, as that was bill watterson's main style.
As for other slight nitpicks, the animation seemed a tad...unbalanced. At times, it was choppy and stiff, at other times, it was overly bouncy and thick, and at times, it was just right.
Still, these are nitpicks and ONLY nitpicks, as it's still wonderful animation of a semi-lovable nostalgic character. Thank you.