Clickers aren't really my thing but I put myself into the shoes of a clicker fan, to try and evaluate fairly. I'm starting to warm up to incrementals in general, they provide pretty good insight into progression curves, rewards and incentives. In that regard, Fireing Fox did a pretty good job keeping me wanting to get the next upgrade, as well as reducing tedium by increasing the heat gained per click.
Art is very cute, and seeing the upgrades affect the scene was charming. I agree with others about wanting an ending, and I had the same idea that the fox might combust if overheated lol. Maybe a forbidden final upgrade.