According to ESRB, this game contains: Mild fantasy violence
Parents should not be concerned. The only action that takes place is a lot of jumping, swinging, and catching bugs with Wik's sticky tongue. The dexterity needed to successfully play the game may be beyond little ones, but there's no content here to be cautious of.
Old-school gamers should definitely check this out. It's a little like Oddworld in many ways and has a lot in common with old 2D platformers. Imagine the first Prince of Persia only more fluid and natural, and then toss in a bunch of bugs and replace the prince with a frog, and then replace the castle with a forest, and then replace… ah, nevermind. It's 2D action that requires nimble fingers and it's great.
Deaf and Hard of Hearing Gamers will have no problems. The only dialogue in the game takes place between levels. There is a telltale sound that plays when grubs appear, or another when each level's requirements are satisfied, but there are also visual cues accompanying the auditory so using the ears isn't much of a factor.