Sonic Racing is a perfectly serviceable mobile kart racer that does nothing wrong but also nothing particularly memorable. It's refreshingly free of the usual mobile game garbage—no gacha mechanics, no constant purchase prompts, no energy timers—which automatically puts it ahead of most mobile titles.
That said, it's clearly a watered-down version of the console game, and kids who've played Mario Kart or the actual Team Sonic Racing will notice what's missing. The 15 tracks sound decent until you realize you'll be replaying them constantly. The AI teammates are fine, the power-ups work, and the multiplayer is functional.
It's the gaming equivalent of a solid B-minus: does the job, won't cause problems, but won't blow anyone away either. If your kid loves Sonic and you need a safe mobile racing option, this works. Just manage expectations that it's mobile-grade, not console-quality.