I have a 3 kids between the ages of 2 years and 11 years. My youngest would definitely enjoy these and I think it's a good start.

It's a very simple idea, so I think you'll need to add some features (pause button, music, more card sets, etc.) to encourage parents to visit often.

Also, I love the domain name and can see that this project was created while scratching your own itch (which is a great way to stay motivated).