Child of Light reminds me in some ways of Studio Ghibli movies: they have a childish aesthetic but are more mature in story and tone. There is an unmistakable somber quality throughout Child of Light, something I wouldn't have expected from a game with a whimsical watercolor art style. This game excels at bringing together elements from various genres and fusing them together into a shining example of innovation for the industry.
Let me list a few of the highlights of the game before I get into a few critiques. This is a gorgeous game, like a living painting with fantastic use of color, interesting inhabitants and exquisite backgrounds. The music stood out from the start and meshed perfectly with the overall tone. The combat showed its depth when I got my greatest enjoyment out of it during my second time through (New Game+ on Hard). A simple but satisfying crafting system allows for customization without too much complexity. Dialogue written in poetry combined with a chapter structure and occasional video cutscenes all add to the moving storybook feel of the game.
Unfortunately this game is not perfect. Some of my complaints, particularly the first one, are matters of personal taste so you'll have to decide for yourself whether what I'm describing sounds like something that would bother you or not. I'm not much of a fan of poetry. At times I did enjoy the rhyming dialogue but other times it seemed like the writers were doing verbal backflips to fit the rhyme in, which made it feel forced and/or obscured the meaning. I do appreciate the novelty of it and how it lends itself to the storybookesque design. Some may dismiss the game as a kid's game due to the childish visuals or playing as a young girl but I urge you not to make that mistake.
Without spoiling anything, I will simply say that the ending felt like it came rather abruptly but was otherwise satisfying. There was a point roughly 2/3rds of the way through my first playthrough that the combat became boring for a time. I was afraid going into my 2nd playthrough (New Game+) that I would be bored with the combat during most of it but that turned out not to be true. The level of challenge on Hard kept me on my toes and making use of all my party member's specialties. I must say that potions are fairly useless in the game. I only used about a dozen in total. Also, don't expect any complex puzzles or platforming. You can fly from nearly the start of the game so traditional platforming goes out the window in favor of mostly manipulating things with your firefly sidekick. Controlling both Aurora with WASD and Igniculus (firefly) with the mouse keeps things interesting.
If I haven't mentioned any aspect you're wondering about go ahead and assume it's good, this game simply oozes quality.