I think you should play the demo when it comes out tomorrow, rather than making a decision based on one person's opinion.
I just finished the game in its completed form for the first time, and I can't wipe the silly grin off my face. The cow race itself just feels *right* -- it's a great blend of tension and puzzles (without ever feeling afraid that you're about to mess up, as is so common in adventure games when the stakes are raised). I really enjoyed the character animations and the dialogue. And unlike Out from Boneville, which ended very abruptly, The Great Cow Race has a really satisfying story arc.
The rereleases of the Bone books are being aimed at children, so it's natural for Telltale to reach out to that audience. But there is a lot for adults to enjoy in the game, both in the humor and in the gameplay.